|Year : 2015 | Volume
| Issue : 2 | Page : 221-229
Neural crest: The fourth germ layer
K Shyamala1, Sarita Yanduri2, HC Girish1, Sanjay Murgod1
1 Department of Oral and Maxillofacial Pathology, Rajarajeswari Dental College and Hospital No. 14, Ramohally Cross, Kumbalgodu, Mysore Road, Bengaluru 560 060, Karnataka, India
2 Department of Oral and Maxillofacial Pathology, DAPMRV Dental College and Hospital, J P Nagar, Bengaluru, Karnataka, India
|Date of Submission||07-Jul-2014|
|Date of Acceptance||01-Jul-2015|
|Date of Web Publication||4-Sep-2015|
Department of Oral and Maxillofacial Pathology, Rajarajeswari Dental College and Hospital, No. 14, Ramohally Cross, Kumbalgodu, Mysore Road, Bengaluru - 560 060, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The neural crest cells (NCCs), a transient group of cells that emerges from the dorsal aspect of the neural tube during early vertebrate development has been a fascinating group of cells because of its multipotency, long range migration through embryo and its capacity to generate a prodigious number of differentiated cell types. For these reasons, although derived from the ectoderm, the neural crest (NC) has been called the fourth germ layer. The non neural ectoderm, the neural plate and the underlying mesoderm are needed for the induction and formation of NC cells. Once formed, NC cells start migrating as a wave of cells, moving away from the neuroepithelium and quickly splitting into distinct streams. These migrating NCCs home in to different regions and give rise to plethora of tissues. Umpteen number of signaling molecules are essential for formation, epithelial mesenchymal transition, delamination, migration and localization of NCC. Authors believe that a clear understanding of steps and signals involved in NC formation, migration, etc., may help in understanding the pathogenesis behind cancer metastasis and many other diseases. Hence, we have taken this review to discuss the various aspects of the NC cells.
Keywords: Delamination, epithelial mesenchymal transition, migration, neural crest cells
|How to cite this article:|
Shyamala K, Yanduri S, Girish H C, Murgod S. Neural crest: The fourth germ layer. J Oral Maxillofac Pathol 2015;19:221-9
| Introduction|| |
Vertebrate head is a complex assembly of cranial specializations such as central and peripheral nervous systems, viscera- and neurocranium, musculature and connective tissue. The vertebrates differ from other chordates primarily in their craniofacial organization. The transition from invertebrate to vertebrate chordates was a multistep process, involving the formation and patterning of many new cell types and tissues. The evolution of early vertebrates was accompanied by the emergence of a specialized set of cells, called neural crest cells (NCC) which have long been the cells of great interest for developmental and evolutionary biologists due to their considerable influence on the complex development of the vertebrate head. 
The NCCs, a transient group of cells that emerges from the dorsal aspect of the neural tube during early vertebrate development has been a fascinating group of cells because of its multipotency, long range migration through embryo and its capacity to generate a prodigious number of differentiated cell types. 
For these reasons, although derived from the ectoderm, the neural crest (NC) has been called the fourth germ layer.  It has even been said, perhaps hyperbolically that "the only interesting thing about vertebrates is the NC" (quoted by Thorogood 1989). 
In view of considerable contribution from NCC, we have taken this review to discuss the various aspects of NC cells.
| History of neural crest|| |
In 1868, a Swiss Embryologist, Wilhelm identified a unique transient embryonic cell population localized in between neural tube and the epidermis in the vertebrate embryo which , he named as Zwischenstrang-the intermediate cord. ,, Arthur Milnes Marshall (1878), appears to have named this intermediate cord as NC cells. Marshall used the term neural ridge for the cells that give rise to cranial and spinal ganglia, a year later, he replaced neural ridge with NC.  Although, initially NCCs were associated with the origins of neurons and ganglia, it was Julia Platt in 1890s, who demonstrated that the visceral cartilages of the head and dentine forming cells of the teeth also arise from the NC (Platt, 1897). This hypothesis of the cranial skeletogenic origins in the NC by Platt gained acceptance 50 years later as it ran counter to the prevailing germ layer theory of the day. Platt's theory was accepted primarily through the seminal work of Sven Horstadius (Horstadius, 1950). , who published a paper in 1950, 82 years after the discovery of the NC titled "The neural crest: Its properties and derivatives in the light of experimental research" which is stands a milestone on the road to understand the NC. 
In view of present evidence of NC as the fourth germ layer giving rise to astonishing number of cells and tissues of the body the following section of this review discusses the induction, epithelial mesenchymal transition (EMT), delamination, migration, regions, derivatives, role in tooth development, multipotency and stemness of NCCs and also to discuss its role in diseases.
| Neural crest induction|| |
NCCs arise uniformly at the dorso-lateral edge of the closing neural folds, along almost the entire length of the vertebrate embryo neuraxis [Figure 1]. This region corresponds to the interface between the nonneural ectoderm (NNE) (presumptive epidermis or surface ectoderm) and the neural plate (neuroepithelium), commonly referred to as the neural plate border (NPB). , With the separation of the neural tube from the surface ectoderm, the cells lying along the dorsolateral sides of the neural tube undergo EMT to form NCCs.  It is evident that induction of the NC requires the presence of NNE, NPB and the mesoderm which is present below the ectoderm. 
|Figure 1: Neural crest cells, epithelial mesenchymal transition, delamination, migration. (concept modified and developed from Mayanil CS. Dev Neurosci 2013;35:361-72)|
Click here to view
At a molecular level it is the bone morphogenetic proteins ( BMP), Wnt and fibroblast growth factor (FGF) pathway which will help to induce the formation of the NCCs.  The BMP and Wnt are produced by NPB and NNE while Wnt and FGF are derived from the mesoderm.  Moreover, Notch/Delta, retinoic acid (RA), Hedgehog and endothelin signaling also contribute to this process. 
NCC induction may be divided into two phases. In the first phase, FGF helps in induction either directly or through Wnt signaling. At this stage, BMP has to be inhibited and for this FGF serves as one of the antagonists. In the second phase, FGF is inhibited, thus, leading to activation of BMP which along with Wnt signaling converge to form a signaling pathway.  As a result of this, a set of transcription factors which specify the NPB (NPB specifiers) are formed. They include Msx1/2, Pax3/7, Zic1, Dlx3/5, Hairy2, Id3 and Ap2. A second set of transcription factors called the NC specifiers are then produced. These are Snail2, Snail FoxD3, Sox9/10, Twist, Id3cMyc and Ap2.  These NC specifiers are very important as they continue to help in the maintenance and ultimately control NC behavior from EMT to migration and differentiation. 
Once formed NCCs undergo EMT, start delaminating into separate cell populations and attain migratory qualities.
| Epithelial Mesenchymal Transition and Delamination: Molecular Orchestrators|| |
Delamination defines the splitting of a tissue into separate populations regardless of the cellular mechanisms.  In contrast, EMT is a series of events at the molecular level bringing about a change from an epithelial to a mesenchymal phenotype.  All NC cells undergo EMT during their development [Figure 2]. 
EMTs are marked by changes in cell adhesion and cell architecture. During delamination the main event that takes place in NCCs is down regulation of cell adhesion molecules. ,,, This switch from strong cell adhesion promotes separation of NCC from the epithelium and allows onset of cell migration. 
NC cells start migrating as a wave of cells, moving away from the neuroepithelium and quickly splitting into distinct streams. ,, These migrating NCCs home into different regions and give rise to plethora of tissues.
Slug and Snail were the first transcription factors to be identified in the NC, about a decade ago.  Snail, slug, sox-9, sox-10 and Foxd-3 genes form a transcriptional network associated with down regulation of the cell adhesion molecules such as N cam, N-cadherin and cadherin 6B and also bring about break down of basement membrane through increase in integrins . ,,,,,
BMP signaling, which is critical for NC induction, also plays a role in NC delamination. Furthermore, Delta-Notch signaling promotes Bmp4 expression and inhibits Slug expression and this could provide a mechanism for effectively controlling the formation and delamination of NC at the neural-epidermal junction.  RhoB is necessary for appropriate delamination of NCCs.  Cadherins control the timing of emigration, delamination and migration. 
Beside changes in cell-cell adhesion, the NCCs undergo a number of modifications in their interactions with the extracellular matrix that are believed to favor their release from the neural tube, which is evidenced by the expression of MMP-2 fostering NC delamination. ,
| Migration of neural crest cells|| |
The capacity for long-range migration through the embryo is the defining feature of NCCs. The journey these cells take across the dynamic landscape of the developing embryo, exposes them to myriad signals from surrounding tissue microenvironments, which vary by developmental site and stage. 
During migration, NC cells are exposed to large number of positive and negative regulators that control where they go by modulating their motility and directionality [Table 1]. [16 ] In addition, as most NC cells migrate collectively, cell-cell interactions play a crucial role in polarizing the cells and interpreting external cues. Cell cooperation eventually generates an overall polarity to the population, leading to directional collective cell migration. 
The pre-NCCs express range of phenotypical adoptions that help them during migration such as filopodia, blebs and the occasional "lobopodium." 
There is evidence of formation of a lamellipodium helping in cellular motility in vitro, along with attachment to a substratum, directional contractile forces and release of the trailing end. ,
These evidences prove that the morphological alterations of NCCs provide them the locomotive properties.
| Regions of the neural crest and their derivatives|| |
The NC can be divided into four main functional (but overlapping) domains:
The number of cell types that arise from the NC is truly astonishing as is the number of tissues and organs [Table 2]  to which the NC contributes. ,
- The cranial (cephalic) NCCs produce the craniofacial mesenchyme that differentiates into the cartilage, bone, cranial neurons, glia and connective tissues of the face. These cells enter the pharyngeal arches and pouches to give rise to thymic cells, odontoblasts of the tooth primordia and the bones of middle ear and jaw 
- The trunk NCCs take one of two major pathways. NCCs of one path become the pigment-synthesizing melanocytes; second migratory pathway takes the trunk NCCs ventrolaterally to each sclerotome and forms the dorsal root ganglia containing the sensory neurons. Those cells that continue more ventrally form the sympathetic ganglia, the adrenal medulla and the nerve clusters surrounding the aorta 
- The vagal and sacral NCCs generate the parasympathetic (enteric) ganglia of the gut ,
- The cardiac NCCs can develop into melanocytes, neurons, cartilage and connective tissue (of the third, fourth and sixth pharyngeal arches). In addition, this region of the NC produces the entire musculoconnective tissue wall of the large arteries as they arise from the heart, as well as contributing to the septum that separates the pulmonary circulation from the aorta. 
|Table 2: A list of the cell types, tissues and organs derived from the neural crest |
Click here to view
| Contribution of neural crest in craniofacial region|| |
The majority of craniofacial connective tissues including those of the dental pulp and periodontal ligament, are formed by a special type of mesenchymal tissue, derived from the NC during embryonic development, thus termed ectomesenchyme.  Ectomesenchyme contributes to the generation of craniofacial structures, such as oral muscles, bones, tongue, craniofacial nerves; and teeth and dental ectomesenchymal stem cells (EMSCs). The ectomesenchyme, therefore, shares a common origin with NCCs. 
The cranial NCCs are central to the process of mammalian tooth development. They are the only source of mesenchyme able to sustain tooth development. Odontogenesis is regulated by a series of interactions between cranial NCCs and the oral epithelium. The oral epithelium provides the first instructive signals by secreting signaling molecules. These signals along proximodistal axis establish large cellular fields competent to form tooth of specific shape, along a rostrocaudal axis define an oral (capable of forming teeth) and nonoral mesenchyme and also helps in positioning the sites of future tooth development. 
| Multipotency and stemness of neural crest cells|| |
As NC can generate a great variety of cell and tissue types it represents a multipotent cell population. Several studies have been performed by Bronner-Fraser and Fraser (1989) and Frank and Sanes (1991) to address the developmental potential and the "stemness" of individual NCCs in vivo., With the establishment of culture systems allowing the analysis of large cell numbers, it became apparent that multipotent cells are relatively frequent among the NCC population.  When grown in a rich medium containing serum, these cells differentiate into a number of NC derivatives.  Later, Stemple and Anderson coined the term neural crest stem cell (NCSC) and showed that NCCs in vitro not only have the ability to give rise to many tissue types but also to self-renew, a unique characteristic of stem cells.  Finally, Calloni et al. have demonstrated the existence of a highly multipotent cell predominantly found in cephalic NC and able to produce clones, comprising cell types as diverse as neurons, glia, melanocytes, chondrocytes, osteoblasts and smooth muscle. 
Researchers have attempted to identify signals supporting the self-renewal of NCSCs. Though still puzzling, the Wnt/BMP signaling with Sox 10 as the downstream target could be maintaining the undifferentiated state of early NCSCs. This theory is supported by the fact that mutation of these genes lead to multiple NC defects. ,,,
| Tooth as a source of nc stemcells|| |
Umbilical cord, the bone marrow and adipose tissue, among others are the best known sources of multipotent mesenchymal stem cells (MSCs) in humans to date.  Whereas Dental and periodontal tissues constitute a relatively recently discovered source of NCSCs. 
Important features and facts of dental EMSC are:
The breakthrough achievement in regenerative dentistry would be to generate a whole functional replacement tooth, out of cultured and dissociated dental stem cells. , However, main hindrance in this research is a lack of consistent source of epithelial stem cells with odontogenic potential that can interact with the mesenchymal tissue. ,
- Substantial amount of EMSC are preserved in the dental pulp and periodontium of both deciduous and permanent teeth.  Amount of cells that can be obtained from a healthy human molar tooth pulp ranges between 500,000 and 2 million 
- As they present a neural crest phenotype they show promising use in nerve tissue restoration. They express neural-progenitor protein markers ,,,
- Dental pulp stem cells (DPSCs) proliferate faster than bone marrow MSCs ,
- DPSCs differentiate to multiple cell lineages including odontoblasts, chondroblasts, adipocytes, muscle cells and neurons in vitro,
- Dental pulp pluripotent stem cells have been recently isolated which express pluripotency markers such as Oct-4, Lin-28, Sox-2 and Nanog ,,
- Periodontal ligament stem cells (PDLSCs) are able to generate cementum and periodontal ligament-like structures including Sharpey's fibers 
- Apical papilla, dental sac or follicle, are the sources of EMSC from a developing toothgerm ,,
- EMSC population can also be isolated from exfoliated human teeth (milk teeth) 
- DPSCs and PDLSCs are good choice for their use in dental and periodontal tissue
- Engineering therapies. 
| Neural Crest Abnormalities: Neurocrestopathies|| |
Neurocrestopathy is a term coined by Bolande in 1974, referring to organ and tissue dysplasias with highly diverse clinical and pathological features caused due to abnormal migration, differentiation and division or survival of NCC [Table 3]. ,
|Table 3: Examples of neurocrestopathies according to compartment and type |
Click here to view
| Conclusion|| |
The neural crest meets all the criteria used to define and identify a germ layer. Ectoderm and endoderm are primary germ layers: Mesoderm is a secondary germ layer formed after inductive interactions between ectoderm and endoderm. Like mesoderm, the neural crest arises early in development and gives rise to divergent cell and tissue types. Basically, neural crest arises by secondary induction from a primary germ layer, hence, meets the criteria of a secondary germ layer.  As the fourth germ layer, the neural crest is confined to vertebrates, which are therefore tetrablastic not triploblastic.  The mechanism of EMT and migration in NCC acts as a model to study malignant tumor cell metastasis as they share striking similarities at molecular level. The multipotency and stemness of NCC can help in regenerative tissue engineering. Hence, a thorough knowledge of NCC may help in understanding a disease process and address these pathological issues.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Trainor PA, Melton KR, Manzanares M. Origins and plasticity of neural crest cells and their roles in jaw and craniofacial evolution. Int J Dev Biol 2003;47:541-53.
Takahashi Y, Sipp D, Enomoto H. Tissue interactions in neural crest cell development and disease. Science 2013; 341: 860-3.
Gilbert SF. The neural crest. Text Book of Developmental Biology. 6 th
ed., Sunderland, MA: Sinauer Associates; 2000.
Hall BK. The neural crest and neural crest cells: Discovery and significance for theories of embryonic organization. J Biosci 2008;33:781-93.
Singh I, Pal GP. Text Book of Human Embryology. 9 th
ed. Newdelhi:Macmillan Publishers India Limited; 2012. p. 283.
Stuhlmiller TJ, García-Castro MI. Current perspectives of the signaling pathways directing neural crest induction. Cell Mol Life Sci 2012;69:3715-37.
Mayanil CS. Transcriptional and epigenetic regulation of neural crest induction during neurulation. Dev Neurosci 2013;35:361-72.
Prasad MS, Sauka-Spengler T, LaBonne C. Induction of the neural crest state: Control of stem cell attributes by gene regulatory, post-transcriptional and epigenetic interactions. Dev Biol 2012;366:10-21.
Steventon B, Mayor R. Early neural crest induction requires an initial inhibition of Wnt signals. Dev Biol 2012;365:196-207.
Thiery JP, Acloque H, Huang RY, Nieto MA. Epithelial-mesenchymal transitions in development and disease. Cell 2009;139:871-90.
Theveneau E, Mayor R. Neural crest delamination and migration: From epithelium-to-mesenchyme transition to collective cell migration. Dev Biol 2012;366:34-54.
Akitaya T, Bronner-Fraser M. Expression of cell adhesion molecules during initiation and cessation of neural crest cell migration. Dev Dyn 1992;194:12-20.
Kimura Y, Matsunami H, Inoue T, Shimamura K, Uchida N, Ueno T, et al.
Cadherin-11 expressed in association with mesenchymal morphogenesis in the head, somite, and limb bud of early mouse embryos. Dev Biol 1995;169:347-58.
Nakagawa S, Takeichi M. Neural crest emigration from the neural tube depends on regulated cadherin expression. Development 1998;125:2963-71.
Kulesa PM, Bailey CM, Kasemeier-Kulesa JC, McLennan R. Cranial neural crest migration: New rules for an old road. Dev Biol 2010;344:543-54.
Theveneau E, Mayor R. Can mesenchymal cells undergo collective cell migration? The case of the neural crest. Cell Adh Migr 2011;5:490-8.
Nieto MA, Sargent MG, Wilkinson DG, Cooke J. Control of cell behavior during vertebrate development by Slug, a zinc finger gene. Science 1994;264:835-9.
Aybar MJ, Nieto MA, Mayor R. Snail precedes slug in the genetic cascade required for the specification and migration of the Xenopus neural crest. Development 2003;130:483-94.
Sasai N, Mizuseki K, Sasai Y. Requirement of FoxD3-class signaling for neural crest determination in Xenopus. Development 2001;128:2525-36.
Aoki Y, Saint-Germain N, Gyda M, Magner-Fink E, Lee YH, Credidio C, et al.
Sox10 regulates the development of neural crest-derived melanocytes in Xenopus. Dev Biol 2003;259:19-33.
Endo Y, Osumi N, Wakamatsu Y. Bimodal functions of Notch-mediated signaling are involved in neural crest formation during avian ectoderm development. Development 2002;129:863-73.
Liu JP, Jessell TM. A role for rhoB in the delamination of neural crest cells from the dorsal neural tube. Development 1998;125:5055-67.
Taneyhill LA. To adhere or not to adhere: The role of Cadherins in neural crest development. Cell Adh Migr 2008;2:223-30.
Martins-Green M, Erickson CA. Basal lamina is not a barrier to neural crest cell emigration: Documentation by TEM and by immunofluorescent and immunogold labelling. Development 1987;101:517-33.
Duong TD, Erickson CA. MMP-2 plays an essential role in producing epithelial-mesenchymal transformations in the avian embryo. Dev Dyn 2004;229:42-53.
Trinkaus JP, Erickson CA. Protrusive activity, mode and rate of locomotion, and pattern of adhesion of Fundulus
deep cells during gastrulation. J Exp Zool 1983;228:41-70.
Lauffenburger DA, Horwitz AF. Cell migration: A physically integrated molecular process. Cell 1996;84:359-69.
Sanz-Moreno V, Gadea G, Ahn J, Paterson H, Marra P, Pinner S, et al.
Rac activation and inactivation control plasticity of tumor cell movement. Cell 2008;135:510-23.
Trainor PA, Krumlauf R. Patterning the cranial neural crest: Hindbrain segmentation and Hox gene plasticity. Nat Rev Neurosci 2000;1:116-24.
Alfandari D, Cousin H, Gaultier A, Hoffstrom BG, DeSimone DW. Integrin alpha5beta1 supports the migration of Xenopus cranial neural crest on fibronectin. Dev Biol 2003;260:449-64.
Strachan LR, Condic ML. Neural crest motility and integrin regulation are distinct in cranial and trunk populations. Dev Biol 2003;259:288-302.
Strachan LR, Condic ML. Neural crest motility on fibronectin is regulated by integrin activation. Exp Cell Res 2008;314:441-52.
Olesnicky Killian EC, Birkholz DA, Artinger KB. A role for chemokine signaling in neural crest cell migration and craniofacial development. Dev Biol 2009;333:161-72.
Smith A, Robinson V, Patel K, Wilkinson DG. The EphA4 and EphB1 receptor tyrosine kinases and ephrin-B2 ligand regulate targeted migration of branchial neural crest cells. Curr Biol 1997;7:561-70.
Adams RH, Diella F, Hennig S, Helmbacher F, Deutsch U, Klein R. The cytoplasmic domain of the ligand ephrinB2 is required for vascular morphogenesis but not cranial neural crest migration. Cell 2001;104:57-69.
Davy A, Aubin J, Soriano P. Ephrin-B1 forward and reverse signaling are required during mouse development. Genes Dev 2004;18:572-83.
Mellott DO, Burke RD. Divergent roles for Eph and ephrin in avian cranial neural crest. BMC Dev Biol 2008;8:56.
Eickholt BJ, Mackenzie SL, Graham A, Walsh FS, Doherty P. Evidence for collapsin-1 functioning in the control of neural crest migration in both trunk and hindbrain regions. Development 1999;126:2181-9.
Gammill LS, Gonzalez C, Bronner-Fraser M. Neuropilin 2/semaphorin 3F signaling is essential for cranial neural crest migration and trigeminal ganglion condensation. Dev Neurobiol 2007;67:47-56.
Schwarz Q, Vieira JM, Howard B, Eickholt BJ, Ruhrberg C. Neuropilin 1 and 2 control cranial gangliogenesis and axon guidance through neural crest cells. Development 2008;135:1605-13.
Yu HH, Moens CB. Semaphorin signaling guides cranial neural crest cell migration in zebrafish. Dev Biol 2005;280:373-85.
Matthews HK, Broders-Bondon F, Thiery JP, Mayor R. Wnt11r is required for cranial neural crest migration. Dev Dyn 2008;237:3404-9.
Hwang YS, Luo T, Xu Y, Sargent TD. Myosin-X is required for cranial neural crest cell migration in Xenopus laevis
. Dev Dyn 2009;238:2522-9.
Nie X, Luukko K, Kettunen P. BMP signalling in craniofacial development. Int J Dev Biol 2006;50:511-21.
Lee YM, Osumi-Yamashita N, Ninomiya Y, Moon CK, Eriksson U, Eto K. Retinoic acid stage-dependently alters the migration pattern and identity of hindbrain neural crest cells. Development 1995;121:825-37.
Pratt RM, Goulding EH, Abbott BD. Retinoic acid inhibits migration of cranial neural crest cells in the cultured mouse embryo. J Craniofac Genet Dev Biol 1987;7:205-17.
Rupp PA, Kulesa PM. A role for RhoA in the two-phase migratory pattern of post-otic neural crest cells. Dev Biol 2007;311:159-71.
Coles EG, Gammill LS, Miner JH, Bronner-Fraser M. Abnormalities in neural crest cell migration in laminin alpha5 mutant mice. Dev Biol 2006;289:218-28.
Drerup CM, Wiora HM, Topczewski J, Morris JA. Disc1 regulates foxd3 and sox10 expression, affecting neural crest migration and differentiation. Development 2009;136:2623-32.
Golding JP, Sobieszczuk D, Dixon M, Coles E, Christiansen J, Wilkinson D, et al.
Roles of erbB4, rhombomere-specific, and rhombomere-independent cues in maintaining neural crest-free zones in the embryonic head. Dev Biol 2004;266:361-72.
Golding JP, Trainor P, Krumlauf R, Gassmann M. Defects in pathfinding by cranial neural crest cells in mice lacking the neuregulin receptor ErbB4. Nat Cell Biol 2000;2:103-9.
Langenberg T, Kahana A, Wszalek JA, Halloran MC. The eye organizes neural crest cell migration. Dev Dyn 2008;237:1645-52.
McLennan R, Kulesa PM. In vivo
analysis reveals a critical role for neuropilin-1 in cranial neural crest cell migration in chick. Dev Biol 2007;301:227-39.
McLennan R, Teddy JM, Kasemeier-Kulesa JC, Romine MH, Kulesa PM. Vascular endothelial growth factor (VEGF) regulates cranial neural crest migration in vivo
. Dev Biol 2010;339:114-25.
Trokovic N, Trokovic R, Partanen J. Fibroblast growth factor signalling and regional specification of the pharyngeal ectoderm. Int J Dev Biol 2005;49:797-805.
Clouthier DE, Williams SC, Hammer RE, Richardson JA, Yanagisawa M. Cell-autonomous and nonautonomous actions of endothelin-A receptor signaling in craniofacial and cardiovascular development. Dev Biol 2003;261:506-19.
Pla P, Larue L. Involvement of endothelin receptors in normal and pathological development of neural crest cells. Int J Dev Biol 2003;47:315-25.
Clouthier DE, Williams SC, Yanagisawa H, Wieduwilt M, Richardson JA, Yanagisawa M. Signaling pathways crucial for craniofacial development revealed by endothelin-A receptor-deficient mice. Dev Biol 2000;217:10-24.
Kuo BR, Erickson CA. Regional differences in neural crest morphogenesis. Cell Adh Migr 2010;4:567-85.
Le Lièvre CS, Le Douarin NM. Mesenchymal derivatives of the neural crest: Analysis of chimaeric quail and chick embryos. J Embryol Exp Morphol 1975;34:125-54.
Billon N, Iannarelli P, Monteiro MC, Glavieux-Pardanaud C, Richardson WD, Kessaris N, et al.
The generation of adipocytes by the neural crest. Development 2007;134:2283-92.
Chai Y, Jiang X, Ito Y, Bringas P
Jr, Han J, Rowitch DH, et al.
Fate of the mammalian cranial neural crest during tooth and mandibular morphogenesis. Development 2000;127:1671-9.
Janebodin K, Horst OV, Ieronimakis N, Balasundaram G, Reesukumal K, Pratumvinit B, et al.
Isolation and characterization of neural crest-derived stem cells from dental pulp of neonatal mice. PLoS One 2011;6:e27526.
Miletich I, Sharpe PT. Neural crest contribution to mammalian tooth formation. Birth Defects Res C Embryo Today 2004;72:200-12.
Bronner-Fraser M, Fraser S. Developmental potential of avian trunk neural crest cells in situ
. Neuron 1989;3:755-66.
Frank E, Sanes JR. Lineage of neurons and glia in chick dorsal root ganglia: Analysis in vivo
with a recombinant retrovirus. Development 1991;111:895-908.
Sommer L. Context-dependent regulation of fate decisions in multipotent progenitor cells of the peripheral nervous system. Cell Tissue Res 2001;305:211-6.
Stemple DL, Anderson DJ. Isolation of a stem cell for neurons and glia from the mammalian neural crest. Cell 1992;71:973-85.
Calloni GW, Le Douarin NM, Dupin E. High frequency of cephalic neural crest cells shows coexistence of neurogenic, melanogenic, and osteogenic differentiation capacities. Proc Natl Acad Sci U S A 2009;106:8947-52.
Kléber M, Lee HY, Wurdak H, Buchstaller J, Riccomagno MM, Ittner LM, et al.
Neural crest stem cell maintenance by combinatorial Wnt and BMP signaling. J Cell Biol 2005;169:309-20.
Britsch S, Goerich DE, Riethmacher D, Peirano RI, Rossner M, Nave KA, et al.
The transcription factor Sox10 is a key regulator of peripheral glial development. Genes Dev 2001;15:66-78.
Herbarth B, Pingault V, Bondurand N, Kuhlbrodt K, Hermans-Borgmeyer I, Puliti A, et al.
Mutation of the Sry-related Sox10 gene in Dominant megacolon, a mouse model for human Hirschsprung disease. Proc Natl Acad Sci U S A 1998;95:5161-5.
Kapur RP. Early death of neural crest cells is responsible for total enteric aganglionosis in Sox10(Dom)/Sox10(Dom) mouse embryos. Pediatr Dev Pathol 1999;2:559-69.
Väänänen HK. Mesenchymal stem cells. Ann Med 2005;37:469-79.
Gronthos S, Mankani M, Brahim J, Robey PG, Shi S. Postnatal human dental pulp stem cells (DPSCs) in vitro
and in vivo
. Proc Natl Acad Sci U S A 2000;97:13625-30.
Huang GT, Gronthos S, Shi S. Mesenchymal stem cells derived from dental tissues vs. those from other sources: Their biology and role in regenerative medicine. J Dent Res 2009;88:792-806.
Davidson RM. Neural form of voltage-dependent sodium current in human cultured dental pulp cells. Arch Oral Biol 1994;39:613-20.
Seo BM, Miura M, Gronthos S, Bartold PM, Batouli S, Brahim J, et al.
Investigation of multipotent postnatal stem cells from human periodontal ligament. Lancet 2004;364:149-55.
Miura M, Gronthos S, Zhao M, Lu B, Fisher LW, Robey PG, et al.
SHED: Stem cells from human exfoliated deciduous teeth. Proc Natl Acad Sci U S A 2003;100:5807-12.
Woods EJ, Perry BC, Hockema JJ, Larson L, Zhou D, Goebel WS. Optimized cryopreservation method for human dental pulp-derived stem cells and their tissues of origin for banking and clinical use. Cryobiology 2009;59:150-7.
Atari M, Barajas M, Hernández-Alfaro F, Gil C, Fabregat M, Ferrés Padró E, et al.
Isolation of pluripotent stem cells from human third molar dental pulp. Histol Histopathol 2011;26:1057-70.
Atari M, Gil-Recio C, Fabregat M, García-Fernández D, Barajas M, Carrasco MA, et al.
Dental pulp of the third molar: A new source of pluripotent-like stem cells. J Cell Sci 2012;125 (Pt 14):3343-56.
Yu J, Vodyanik MA, Smuga-Otto K, Antosiewicz-Bourget J, Frane JL, Tian S, et al.
Induced pluripotent stem cell lines derived from human somatic cells. Science 2007;318:1917-20.
Gronthos S, Brahim J, Li W, Fisher LW, Cherman N, Boyde A, et al.
Stem cell properties of human dental pulp stem cells. J Dent Res 2002;81:531-5.
Sonoyama W, Liu Y, Fang D, Yamaza T, Seo BM, Zhang C, et al.
Mesenchymal stem cell-mediated functional tooth regeneration in swine. PLoS One 2006;1:e79.
Bakopoulou A, Leyhausen G, Volk J, Tsiftsoglou A, Garefis P, Koidis P, et al.
Comparative analysis of in vitro
osteo/odontogenic differentiation potential of human dental pulp stem cells (DPSCs) and stem cells from the apical papilla (SCAP). Arch Oral Biol 2011;56:709-21.
Morsczeck C, Götz W, Schierholz J, Zeilhofer F, Kühn U, Möhl C, et al.
Isolation of precursor cells (PCs) from human dental follicle of wisdom teeth. Matrix Biol 2005;24:155-65.
Anitua E, Sánchez M, Nurden AT, Nurden P, Orive G, Andía I. New insights into and novel applications for platelet-rich fibrin therapies. Trends Biotechnol 2006;24:227-34.
Ikeda E, Morita R, Nakao K, Ishida K, Nakamura T, Takano-Yamamoto T, et al.
Fully functional bioengineered tooth replacement as an organ replacement therapy. Proc Natl Acad Sci U S A 2009;106:13475-80.
Oshima M, Mizuno M, Imamura A, Ogawa M, Yasukawa M, Yamazaki H, et al.
Functional tooth regeneration using a bioengineered tooth unit as a mature organ replacement regenerative therapy. PLoS One 2011;6:e21531.
Shinmura Y, Tsuchiya S, Hata K, Honda MJ. Quiescent epithelial cell rests of Malassez can differentiate into ameloblast-like cells. J Cell Physiol 2008;217:728-38.
Nakagawa E, Itoh T, Yoshie H, Satokata I. Odontogenic potential of post-natal oral mucosal epithelium. J Dent Res 2009;88:219-23.
Bolande RP. The neurocristopathies: A unifying concept of disease arising in neural crest mal development. Hum Pathol 1974;5:409-29.
Etchevers HC, Amiel J, Lyonnet S. Molecular bases of human neurocristopathies. Adv Exp Med Biol 2006;589:213-34.
Miletich I, Sharpe PT. Normal and abnormal dental development. Hum Mol Genet 2003;12 Suppl 1:R69-73.
Behan PO, Chaudhuri A. The sad plight of multiple sclerosis research (low on fact, high on fiction): Critical data to support it being a neurocristopathy. Inflammopharmacology 2010;18:265-90.
Carstens MH. Neural tube programming and craniofacial cleft formation. I. The neuromeric organization of the head and neck. Eur J Paediatr Neurol 2004;8:181-210.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]