|Year : 2022 | Volume
| Issue : 1 | Page : 32-37
Regenerative capacity of the dental mesenchymal stem cells and their implications in dentistry
KV Sai Charan, M Kumari, VS Gayathri
Department of Oral Medicine and Radiology, Ragas Dental College and Hospital, Chennai, Tamil Nadu, India
|Date of Submission||30-Jan-2022|
|Date of Decision||15-Feb-2022|
|Date of Acceptance||18-Feb-2202|
|Date of Web Publication||14-Mar-2022|
Dr. K V Sai Charan
No: 2956, T.N.H.B, Avadi, Chennai - 600 054, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Stem cells perform a crucial role in tissue growth, development, and repair. Stem cell has been identified to possess unique and extensive properties that define their possible application in the field of regenerative medicine. Regenerative medicine is a branch that is grounded on the application of stem cells capable of multidirectional differentiation or employing biological products. The use of dental stem cells is emerging as an innovative approach in the treatment of various dental disorders. Standard dental treatments usually rely on the use of artificial materials or relatively nonconservative treatments. Regenerative dental procedures involving mesenchymal stem cells (MSCs) have the potential of becoming a valuable alternative to standard treatments. This review explores the basics of oral MSCs in the field of Regenerative Medicine.
Keywords: Barriers, cryopreservation, isolation, mesenchymal stem cell, scaffolds, stem cell banks
|How to cite this article:|
Sai Charan K V, Kumari M, Gayathri V S. Regenerative capacity of the dental mesenchymal stem cells and their implications in dentistry. SRM J Res Dent Sci 2022;13:32-7
|How to cite this URL:|
Sai Charan K V, Kumari M, Gayathri V S. Regenerative capacity of the dental mesenchymal stem cells and their implications in dentistry. SRM J Res Dent Sci [serial online] 2022 [cited 2022 May 16];13:32-7. Available from: https://www.srmjrds.in/text.asp?2022/13/1/32/339633
| Introduction|| |
Regenerative medicine is a branch which is grounded on the application of stem cells capable of multidirectional differentiation or employing biological products including platelet-rich plasma, or its gel formulation platelet gel, which are capable of inducing the stem cell migration toward the area of damaged tissue region, to enhance their proliferative potential and to ultimately gain tissue repair. Regenerative medicine is a field which in corporates several approaches, including the use of bio-materials, de novo cells with several combinations thence, to inhabit the place of missing tissues, efficiently substituting it both morphologically and functionally, in turn, promoting tissue healing. Owing to the improvements in biotechnology and medicine, a surplus of technologies has been made accessible. Area of medicine is being continuously upgrading day to day, protocol/modality which is considered for treatment now may become superseded by newer advancement in upcoming years. Regenerative medicine was once considered as an entity of the distant future, yet now we could encounter a variety of regenerative procedures being accomplished in a daily practice. Recently, dental therapies are focussing on tissue biology and aimed toward the regeneration of tissue, nowadays in the field of medicine, mostly all treatments are based on a tissue biology and the modern advances in genomics, cell analysis, and stem cells are uplifting fields of medicine on the way to a new eon. Yet, these advancements are not completely being incorporated into dental field. Dentistry should embrace these developments and should start its major travel in introducing various biological material-based incremental enhancements in the treatment protocol. Based on the information gathered from various research papers and schematic reviews, there was no manuscript describing the complete data regarding oral mesenchymal stem cell (MSCs) and their application, tissue engineering, and their proliferative potential. In this review, we intend to discuss the regenerative capacity of oral MSCs, dental stem cell isolation methods, potential clinical applications, and their barriers in application.
| Oral Cavity, a Reservoir for Mesenchymal Stem Cells|| |
International society for cellular therapy has defined MSCs as a cell that satisfies the proposed minimum criteria including exhibitance of plastic adherence, possess a specific set of cell surface markers (CD73, D90, CD105, STRO-1, TNAP and they lack expression of CD34, CD45, CD15, and human leukocyte antige-DR), and ability to differentiate in vitro into osteoblast, chondrocyte, and adipocyte., Oral MSCs can be classified as dental MSCs and nondental MSCs. Dental MSCs include dental pulp stem cell (DPSC), stem cell from apical papilla, and stem cell from the exfoliated deciduous tooth. Nondental stem cell includes periodontal ligament stem cell (PDLSCs) and MSCs from the gingiva. Although MSCs are isolated from a variety of tissues including adipose tissue, bone marrow, etc., this oral mesenchymal cell has an ability for multidirectional differentiation, the difference in the site of origin can have an impact in their differentiating potential. MSCs extracted or isolated from the oral tissues may be much operative when compared to stem cells isolated from adipose tissue in treating the dental defects. Thus, the oral cavity might serve as a great reservoir of MSCs, restricted in a specific well-characterized tissue. Application of dental mesenchymal stem cells given in [Table 1].,,
Dental pulp stem cell
DPSCs possesses an ability that renders it to be used in regeneration, for the treatment of a variety of diseases/disorder even including dental disorders. DPSCs can differentiate into odontoblast-like cells and thereby aid in laying down the reparative dentin which holds up its applications in dentistry for regeneration of tooth structures. It also possesses properties similar to stromal cells originating from bone marrow which supports its application in musculoskeletal regenerative medicine. DPSCs have neurogenic potential because it traces its origin from the neural crest., A major problem encountered in the usage of DPSC is that only a few number of cells will be obtainable from isolation, owing to the insignificant proportions of the pulp. Obtaining adequate cells for therapeutic application will necessitate multiple passages that may lower the potential of the cultured stem cells. DPSCs commonly present in the dental pulp in perivascular niche probablystemming from the pericytes may bring about angiogenesis in vivo. Angiogenic potential of DPSCs is most likely due to the production of vascular endothelial growth factor. DPSCs can also be differentiated into neuron-like cells in culture and even expressed the specific neuronal marker Nestin, thus upholds the point that it can be used in nerve regeneration in neurological disorders. The potency of DPSCs for multidirectional differentiation into pancreatic cell lineage resembled islet-like cell aggregates resulting in glucose-dependent release of insulin and C-peptide in-vitro. Replacing the missing (insulin-producing cells [IPC]), can be done either by transplantation of islet cells or by a stemcell that is differentiated into IPC, which might be an ideal method for the treatment of diabetes. The capacity of DPSCs in periodontal tissue regeneration is still under dispute for their partial potential in cementum formation.
Stem cells from human exfoliated deciduous tooth
SHED is derived from the dental pulp as DPSC from the exfoliated tooth. It exhibits a higher level of gene expression which includes NANOG, SOX2, REX-1, and OCT4 related toward its stemness in comparison to DPSCs, exhibiting a higher plasticity. Their proliferation rates are higher and are capable of differentiating into osteoblasts but their limitation is an inability to renew dentin and pulp tissue as a whole in vivo., SHED possess a high proliferative potential and is proficient of multidirectional differentiation, that is it can differentiate into a variety of cell types which includes neuronal cells, adipocytes, osteoblast, and chondrocytes. This stem cell even traces its origin from perivascular tissue with pericyte-like features, thus making them to differentiate into endothelium. The osteoinductive capacity has been investigated in vivo – the findings are it could repair calvarial defects of critical size with the active formation of bone. Osteogenic potential of SHED may be improved when tend to be cultured in scaffolds made of chitosan which comprises divalent metal phosphates, displaying the substantial raise in differentiation of osteoblastin comparison to the cells cultured without a divalent metal phosphate. When a comparison is made between SHED isolated via enzymatic disaggregation and out growth by primary culture method, SHED via enzymatic disaggregation have stemness characteristics, and are mostly appropriate for bone tissue regeneration therapy.
Periodontal ligament stem cells
PDLSCs plays a prominent role in regeneration and in the maintenance of PDL homeostasis, attachment of tooth to bony component, and in mastication. PDLSCs have an ability to differentiate/delineate into cementoblast-like cells. They are even capable of establishing a connective tissue which is rich in Type I collagen fibers. Periodontal ligament comprises a group of stem cells that are capable of expressing MSCs surface markers, potential for self-renewal, and possess a multipotency that is able to distinguish into a variety of cells including cementoblast, adipocytes, osteoblast, and collagen-forming cell. The osteoinductive potency of PDLSCs is much less prominent than DPSCs and SHED but is capable of regenerating PDL tissue. The prevalence of the transforming growth factor β1 (TGF-β1) signaling is the crucial mechanism which acts behind to determine whether these stem cells could be differentiated into periodontal ligament predecessors or cementoblasts. Certainly, TGF-β1 inhibition obstructs the cementoblastic differentiation potential but encourages fibroblastic differentiation. Furthermore, PDLSCs express a protein scleraxis which is considered to be a tendon/ligament-specific transcription factor, responsible for chondrogenesis and tendon development at a greater level in comparison DPSCs, signifying PDLSCs heightened capability to regenerate and renew PDL tissue. Bortezomib is the proteasome inhibitor that possesses the capacity of persuading osteoblast formation by differentiation of PDSLSs. A core process behind this is the mineralization of PDLSCs cells by accretion of β catenin and Bone morphogenetic protein (BMP2) gene expression. The compound comprising concentrated growth factor and (conditioned medium-PDLSCs carried by hydroxyapatite/tri-calcium phosphate) may be effective in endorsing PDLSCs proliferation, demonstrating this product may be beneficial for future applications in periodontal regeneration.,,
Dental follicle stem cells
Dental follicle stem cells (DFSCs) be inherent in the connective tissue which is loosely bound seen adjacent to the evolving tissue and is responsible for the formation of alveolar bone and root-bone interface. DFSCs express a higher potential for proliferation and osteogenic characteristics when compared to other dental MSCs. DFSCs are a kind of immature stem cells that express more (dentin sialophosphoprotein) than PDLSCs. Certainly, they display an obvious odontogenic potential being capable of regenerating dentin tissue and have probable periodontal regeneration capabilities and root rejuvenation. DPSCs and DFSCs possess an analogous kind MSCs property, whereas DFPCs are readily accessible for cell culture and have a greater proliferation potential than the DPSCs. Hence, it indicates that DFPCs could be more significant as a stem cell reserve for therapies related to dental regeneration. Recently, isolated DFSCs were found to initiate the formation of salivary gland parenchymal cells and ductal cells. DFSCs may also play a significant role in the management of inflammatory diseases and autoimmune diseases evident in animal models.,
Gingival mesenchymal stem cells
In animal model, these stem cells encourage a macrophage polarization and hinder the activity of osteoclast, thus preventing bone resorption thus portraying the immunomodulatory potency as the other MSCs. Gingival MSCs (GMSCs) display an ease in accessibility certainly, they can readily isolated from healthy gingival tissues, inflamed gingival tissue, or even from cast off dental tissue samples too. GMSCs possess an osteogenic potency demonstrated in vitro. In extracellular vesicles obtained from GMSCs, cytokines RUNX2 and BMPs expression were significantly higher which are capable of promoting extracellular matrix formation and mineralization of new bone.,,
Buccal fat pad stem cell
It is capable of repairing bony defects, it can be used in combination with inorganic bovine bone mineral for bone repair.
Stem cells from apical papilla
The apical papilla is a mass of tissue inherent in the developing permanent teeth in apical region, apical papilla is considered to be a pioneer tissue in the radicular portion of the pulp, augmented with cells of high capacity of proliferation. Their proliferation rates besides its differentiation characteristics are similar to DPSCs. These cells have the potential of distinguishing into odontoblasts. It may form a layer of dentin in vivo. Stem cells from apical papilla (SCAPs) are considered an appropriate type of stem cell that can be used in cell-based therapy in establishing theroot apex. The substance white mineral trioxide aggregate a capping material possesses an inherent property that differentiates SCAPs into osteoblasts. This aggregate proficiently rises the rate of proliferation of SCAPs within 1–5 days. Renewal of intricate perilous size defects in the maxillofacial region is difficult, but exosomes derived from this kind of cells promote regeneration of tissue in vivo by promoting vascularization in the defective area.,
| Isolation of Stem Cell|| |
Isolating a stem cell is a crucial procedure and involves extreme care. Two methods are used to execute the isolation of MSCs.
- Enzymatic digestion (collagenase and dispase)
- Primary culture/Explant.
The enzymatic digestion method involves the process of incorporation of an enzyme collagenase I and dispase in straight contact within the extracted tissue, appropriate to disaggregate the tissue and acquire cell suspension. In this method, the released stem cells can adhere rapidly to the bottom of the culture dish.
Primary culture or explant
In this explant technique, the tissue does not undergo any cell dissociation, but the tissue is fragmented into several pieces and is deposited on culture dishes. The stem cells existing will migrate slowly from the tissue to the bottom of the dishes, thus establishing a primary culture. Due to the diminished cell viability associated with the enzymatic digestion method, the explant/primary outgrowth has been recommended as a technique of choice.
| Tissue Engineering in Regeneration|| |
Tissue engineering is concerned with the efficient replacement/restoration of the tissue's structure and function for damaged or destructed tissue due to neoplasm, disease, and traumatic incident. It involves three key elements that include stem cells, scaffolds, and morphogens.
Stem cells possess an exclusive and comprehensive capability, defining their probable application in regeneration. Stem cells are considered as precursor cells categorized by two inimitable capabilities: (1) self-renewal and (2) differentiation. Depending on the stem cell type and their capability and potential to differentiate into various tissue, they are been broadly classified into totipotent, pluripotent, and multipotent. The dental stem cells used in regenerative therapies have been dealt with elaborately in the above paragraphs.
It is defined as a framework that holds the cells/tissues together. Characteristics of scaffold include (1) should contain growth factor in it to hasten the growth, proliferation, and differentiation of stem cell, (2) must be efficient for the transportation of nutrients, oxygen, and waste products, (3) possess an appropriate pore size to enable seeding of cell and diffusion, (4) rate of degradation of scaffold should coincide with the rate of tissue formation, (5) must possess structural integrity and it should, in the end, break down leaving the newly formed tissue.
Scaffolds have been broadly categorized as natural and synthetic types.
- Natural (collagen, chitosan – poly N acetyl glycosaminoglycans)
- Artificial (polyglycolic acid, polylactic acid, polycaprolactone, Tri-calcium phosphate (TCP), hydroxyapatite (synthetic variety), polyethylene glycol).
The advancements in the generation of a micro-engineered type of scaffold are upholding the outlines of progenitor cells which are capable of differentiation to specific kind tissues, morphogens, and signaling molecules to mediate/direct cell behavior, reinforcement by a structured microvasculature might also provide expeditious and strong techniques for the tooth generation in vitro.
| Morphogens|| |
Growth factors/morphogens are known as extracellular matrix molecules, responsible for signaling, and act as regulators in the events during tooth development and maturation. Applying these exogenous signaling factors is now being recommended for the therapies involving regeneration.
Morphogens available naturally and commercially which are considered osteogenically active growth factors are as follows.
- Bone morphogenic/morphogenetic protein (BMP)
- Platelet-derived growth factor
- Insulin-like growth facto
- Fibroblast growth factor
- Dentine sialoprotein
- Dentine phosphoprotein
- Enamel matrix Derivative.,
| Clinical Applications|| |
DPSCs seeded in poly-lactide-co-glycolide scaffold filled in the canal space, regeneration of pulp-dentin-like tissue was evident, and it produced a constant overlay with the unique dentinal surface, this experiment is studied using tooth fragments containing enlarged root canal. In recent years, pulp regeneration was accomplished completely in a permanent canine which was subjected to pulpectomy after that autologous progenitor cell with a morphogen stromal cell-derived factor-1 is then inserted into a canal space which resulted in complete root generation. Stem cells + morphogens on scaffold implanted into canal space in that freshly isolated healthy pulp tissues comprising of large apical foramen showed high rates of capability of regeneration rather than diseased pulp tissue. Comparison between the cells obtained from apparently healthy dental pulp and inflamed dental pulps concerning about the residence, their potential for proliferation and differentiation capacity was studied which revealed that the inflammed dental pulp tissue encompasses vital cells with the ability of growth and proliferation, alike proportion of STRO-1 (surface marker for MSC marker) and osteogenic and odontogenic differentiation ability. Although the inflammed pulp tissue comprise conserved stem cells, it could be predicted as an appropriate reservoir of DPSCs for dental pulp regeneration, so it must not be justcastoff as biological waste.,
Embedding of DPSCs onto a periodontal defect in an animal model resulted in the rejuvenation of well-established matured bone tissue along with neo-vascularization. DPSCs seeded in collagen scaffold implanted in the extracted mandibular third molar region led to the comprehensive regeneration of defective bone at the extracted site. Most recently, the human trial has been established with a cell-coated implant which is then embedded in the mandibular region, PDL generation around the implant surface was evident in the clinical study. The above-mentioned model, ligaplants, combines PDL progenitor cells with implant and it demonstrated successful function on observation over 60 months. This evidence upholds the greatest probability for PDLSCs as a substitute method to osseointegrated dental implants, which may provide well-organized technique to augment the outcome of implant treatment.
SCAP are capable of differentiating into odontoblast-like cells along with an active migration potential and mineralization capability, owing toward the formation of systematized dentin-like structures in vitro. When SCAP on hydroxy-apatite scaffolds are rooted subcutaneously in immune compromised animal-model, bony tissue and mineralized dentinal structures were renewed within 60 days following implantation of this bio-complex. SHED in conjunction with hydroxy-apatite/TCP restored perilous-sized calvarial defects in animal-model with the significant formation of bone. SHED might segment similar tissue origin with the mandibular bony cells and henceforth will assist as an improved cell source for the alveolar bone regeneration and even in the defects of orofacial region.
The apical papilla is considered to play a crucial part in the formation of root. In an animal model, Hydroxyapatite/TCP segment comprising of SCAP layered with Gelfoam which, in turn, consist of PDLSCs designed in the shape of the root when transplanted onto the socket of a recently extracted site. The findings were after 12 weeks, the bioroot formation was evident which accomplished a support for artificial crown. This evidence indicates the practicability of combining the autologous SCAP + PDLSCs for efficient tooth regeneration.
| Barriers Encountered in the Field of Regenerative Dentistry|| |
The prime obstacle faced is recognizing a method of introducing tooth embryonic-like characteristics to adult matured cells. Nonaccessibility of autologous embryonic tooth germ cells for human applications is another major challenge. Xeno-genic stem cells (stem cell from other species) might provoke immune rejection and altered tooth morphology. Nevertheless, the source, the Cell-delivery methods for regeneration of tooth, come across transportation barriers. Expenses of these procedures and regulations regarding approval have halted the substantial clinical translation effort in tooth regeneration. Regeneration of teeth and its associated structures by a method of cell transplantation come across numerous systematic, translational, and regulatory affairs.
| Cryopreservation and Banking of Stem Cells|| |
After vital pulp cells have been isolated, it should be kept magnificently in a frozen state and should be stored. The isolated cells must be incorporated in a medium encompassing growth factors and dimethyl sulfoxide-(a cryoprotectant) → primarily impedes the growth of ice crystals as it might interrupt the membrane of the cell therefore reduces vitality. It is then transported into a focused cryo-vials commonly made out of polypropylene. Then, the samples are freezed and positioned in low-temperature storage flasks containing the liquid nitrogen. Freezing procedure followed in cryopreservation consists of as low/staged freezing accompanied by long-term storage in the presence of liquid nitrogen which sustains the samples below 195.8°C/320.5°F. In countries such as US, India, and UK, dental stem cell banks are increasing in number.,
Remarkably, these oral-MSCs possess a regenerative capacity not only to distinguish has dental cells but also is capable of regenerating other types of cells such as neural cells, muscles cells, bone cells hepatic cells, pancreatic cells, and cardiac cells, etc., with proper signaling and environmental conditions. During the process pf sub-culturing and further high passages, these cells might lose their proliferation potential. The oral microbial flora, the inflammation rate, and the self-adaptive remodeling of the alveolar bone play the important role in sustaining the homeostasis of rima oris. Once inflammation overrules, irreversible conditions can occur, which lands into disease of periodontium and alveolar bone destruction. The multidirectional differentiating potency and anti-inflammatory property of MSCs make them be utilized in regenerative therapies. Matured MSCs which has been isolated from various tissues demonstrate an extensive multidirectional differentiation. Since MSCs retains the memory of their site of origin, which has the ability to replace the diseased/destructed tissue of the oral cavity/other areas, thus application of oral-derived MSCs is desirable for replacement of destructed/damaged oral tissues. The MSCs which trace their origin from the oral cavity are considered to be a multipotent cell which is affordable and can be isolated noninvasively. Current advancements in the field of biotechnology have reinvigorated investigators to explore whether there is a possibility of regeneration with functional properties through the help of scaffold + DPSCs cells. Recently, oral MSCs has been found to possess anti-microbial activity.
| Conclusion|| |
The noninvasive methods of isolating the oral-MSCs when compared to stem cells derived from other tissues mark them as a significant probable source for the management of several diseases. In the near future, advancements in the field of stem cell research and tissue engineering might replace the damaged tissue with the help of regenerative therapies.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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