Stem cells are the bodys "master" cells thatregenerate the bodys many cells, tissues, andorgans. Most cells in your body can only make newcells of the same type - blood cells make bloodcells, skin cells make more skins cells and so on.Stem cells are unique not only because they canturn into many different types of cells - a stem cellmight create blood, kidney, heart, or bone forexample - but also because they can divide manymore times than other cells.
There are two broad types of stem cells: embryonicstem cells and adult stem cells.While there has been much debate on the ethicalissues surrounding the use of embryonic stem cells,adult stem cells are free of this controversy and onlyadult stem cells, to date, have been used to treatpeople.
The most commonly known source of adult stemcells is bone marrow, which contains bothhematopoietic stem cells (also found in cord blood)and mesenchymal stem cells (also found in teeth).
DENTAL STEM CELLS AND TRANSFER FACTORS Tooth infections or injuries involving dental pulp are treated routinely by root canal therapy. Endodontically treated teeth are devitalized, susceptible to re-infections, fractures, and subsequent tooth loss. Here, we report regeneration of dental-pulp-like tissue by cell homing and without cell transplantation. Upon in vivo implantation of endodontically treated real-size, native human teeth in mouse dorsum for the tested 3 weeks, delivery of basic fibroblast growth factor and/or vascular endothelial growth factor (bFGF and/or VEGF) yielded re-cellularized and revascularized connective tissue that integrated to native dentinal wall in root canals
Further, combined delivery of bFGF, VEGF, or platelet-derived growth factor (PDGF) with a basal set of nervegrowth factor (NGF) and bone morphogenetic protein-7(BMP7) generated cellularized and vascularized tissuespositive of VEGF antibody staining and apparent neo-dentinformation over the surface of native dentinal wall in some,but not all, endodontically treated teeth. Newly formeddental pulp tissue appeared dense with disconnected cellssurrounded by extracellular matrix. Erythrocyte-filled bloodvessels were present with endothelial-like cell lining.
Reconstructed, multiple microscopic images showedcomplete fill of dental-pulp-like tissue in the entire rootcanal from root apex to pulp chamber with tissueintegration to dentinal wall upon delivery of bFGF, VEGF,or PDGF with a basal set of NGF and BMP7. QuantitativeELISA showed that combinatory delivery of bFGF, VEGF,or PDGF with basal NGF and BMP7 elaborated vonWillerbrand factor, dentin sialoprotein, and NGF. Thesefindings represent the first demonstration of regenerateddental-pulp-like tissue in endodontically treated rootcanals of real-size, native human teeth
The present chemotaxis-based approach has potent cellhoming effects for re-cellularization and revascularizationin endodontically treated root canals in vivo, although inan ectopic model. Regeneration of dental pulp by cellhoming, rather than cell delivery, may accelerate clinicaltranslation.
Anatomy of dental pulpThe dental pulp is the part in the center of a tooth made upof living soft tissue and cells called odontoblasts. The centralregion of the coronal and radicular pulp contains large nervetrunks and blood vessels. This area is lined peripherally by aspecialized odontogenic area which has three layers whichare (from innermost to outermost): cell rich zone, cell freezone and odontoblastic layer.
During tooth formation, interactions betweenepithelial and dental papilla cells promote toothmorphogenesis by stimulating a subpopulation ofmesenchymal cells to differentiate intoodontoblasts, which in turn form primary dentin.These odontoblasts are thought to arise from theproliferation and differentiation of a precursorpopulation, residing somewhere within the pulptissue
Types of dental stem cells:At least five different types of postnatalmesenchymal stem cells have been reported todifferentiated to odontoblast-like cells.
1.dental pulp stem cells(DPSC)2.dental pulp of human exfolliated deciduousteeth(SHED)3.stem cells of apicall papilla(SCAP)4.Dental follicle progenitor cells(DFPC)5.Bone marrow-derived mesenchymal stemcells(BMMCS)
1.Dental pulp stem cells: (DPSCs) represent a kind of adult cell colony which has thepotent capacity of self-renewing and multilineage differentiation.The exact origin of DPSCs has not been fully determined andthese stem cells seem to be the source of odontoblasts thatcontribute to the formation of dentin-pulp complex. Recently,achievements obtained from stem cell biology and toothregeneration have enabled us to contemplate the potentialapplications of DPSCs. Some studies have proved that DPSCsare capable of producing dental tissues in vivo including dentin,pulp, and crown-like structures. Whereas other investigationshave shown that these stem cells can bring about the formationof bone-like tissues. Theoretically, a bio-tooth made fromautogenous DPSCs should be the best choice for clinical toothreconstruction.
2.Dental pulp of human exfolliateddeciduous teeth contains multipotent stem cellsfrom humanexfoliated deciduous teeth (SHED). wereidentified to be a population of highly proliferative, clonogeniccells capable of differentiating into a variety of cell typesincluding neural cells, adipocytes, and odontoblasts. Thus,exfoliated teeth may be an unexpected unique resource forstem-cell therapies including autologous stem-celltransplantation and tissue engineering.
3.Stem cells of apical papillaA unique population of dental stem cells known asstem cells from the root apical papilla (SCAP) islocated at the tips of growing tooth roots . The apicalpapilla tissue is only present during root developmentbefore the tooth erupts into the oral cavity . SCAPhave the capacity to differentiate into odontoblastsand adipocytes .These cells are CD24+ butexpression is downregulated upon odontogenicdifferentiation in vitro coincident with alkalinephosphatase upregulation
4.Dental follicle progenitor cells:The dental follicle is a loose ectomesenchyme-derived connective tissue sac surrounding theenamel organ and the dental papilla of thedeveloping tooth germ before eruption . It isbelieved to contain progenitors for cementoblasts,PDL and osteoblasts. Dental follicle cells (DFC)form the PDL by differentiating into PDL fibroblaststhat secrete collagen and interact with fibres on thesurfaces of adjacent bone and cementum
5. bone marrow derrived cells:Bone marrow-derived cells (BMDCs) have thepotential to engraft into several tissues afterinjury, but whether they can become dentaltissue-specific progenitor cells under normalconditions and the relationship of these cells tothe tissue-resident cells are unknown. bone marrow progenitor cells communicate withdental tissues and become tissue-specificmesenchymal progenitor cells to maintain tissuehomeostasis.
INDICATION1.Dental tissue repair: dental stem cells are currently considered to offer potential fortissue regeneration. These include the obvious uses of cells to repair damaged tooth tissues such as dentine, periodontalligament and dental pulp Even enamel tissue engineering hasbeen suggested as well as the use of dental stem cells assources of cells to facilitate repair of non-dental tissues suchas bone and nerves
2.Periodontal regeneration:The periodontium is a set of specialized tissues thatsurround and support the teeth to maintain them in the jaw.Periodontitis is an inflammatory disease that affects theperiodontium and results in irreversible loss of connectivetissue attachment and the supporting alveolar bone. Thechallenge for cell-based replacement of a functionalperiodontium is therefore to form new ligament and bone,and to ensure that the appropriate connections are madebetween these tissues, as well as between the bone andtooth root. . One aim of current research is to use differentpopulations of dental stem cells to replicate the key eventsin periodontal development both temporally and spatially, sothat healing can occur in a sequential manner to regeneratethe periodontium
4.Regeneration of dental pulp inimmature toothDental pulp needs to be removed when it becomesinfected, and this is particularly problematic for root pulpthat requires endodontic (root canal) treatment. Therestoration of tooth pulp is thus a much sought after goalin dentistry because the current practice of replacinginfected pulp with inorganic materials (cements) results ina devitalized (dead) tooth. A recent study demonstrated denovo regeneration of dental pulp in emptied root canalspace using dental stem cells .
5.Whole tooth regeneration:The current state of the art in tooth replacement is adental implant that involves screwing a threaded metalrod into a predrilled hole in the bone, which is thencapped with a plastic or ceramic crown. Implant userequires a minimum amount of bone to be present.Because these implants attach directly to the bonewithout the PDL ‘shock absorber’, the forces ofmastication are transmitted directly to the bone, which isone reason implants can fail. In cases where there isinsufficient bone for implants, such as tooth loss as aconsequence of the bone loss that occurs inpostmenopausal osteoporosis, implants have to bepreceded by bone grafts. The ultimate goal in dentistryis to have a method to biologically replace lost teeth; in
Techniques:a.The idea is to take adult stem cells, treat themin a cell culture so they would be programmed todevelop into teeth and then transplanted into thepatients jaw where the gap is. Then areplacement tooth grows just as happens whenhumans grow their original adult teeth. It isthought it would then take two to three monthsfor the tooth to fully develop. The cost should notbe more than existing treatments making it anattractive alternative to other technologies suchas implants and dentures.
b.The tooth bud is then implanted in the jaw andthe gum stitched or sealed with a clinical "glue".They have not started human clinical trials yet,however they expect the procedure to be lessinvasive than a tooth extraction and therequirements for post-procedure care would besimilar. After implantation it takes the tooth about 3weeks to set in the jaw of a mouse. As long as thetooth is not under heavy load, it sets well.The technology to grow replacement teeth couldmean the end of dentures
Advantages1.It provides medical benefits in the fields of therapeuticcloning and regenerative medicine.2.It provides great potential for discovering treatmentsand cures to a plethora of diseases including Parkinsonsdisease, schizophrenia, Alzheimers disease, cancer,spinal cord injuries, diabetes and many outhers3.Regenerated pulp can re-build a damaged tooth fromthe inside4• Tooth with a regenerated pulp will require markedlysmaller restorations5• Tooth with a regenerated pulp may uphold theproprioceptive function of the tooth
Disadvantages:1.The use of embryonic stem cells involves thedestruction of blastocysts formed from laboratory-fertilized human eggs. For those people who believe thatlife begins at conception, the blastocyst is a human lifeand to destroy it is immoral and unacceptable.2.Like any other new technology, it is also completelyunknown what the long-term effects of such aninterference with nature could materialize.3. These are derived from embryos that are not apatients own and the patients body may reject them.
SummaryTooth Stem Cells Therapeutic PotentialThe ultimate goal of tooth regeneration is to replacethe lost teeth. Stem cell-based tooth engineering isdeemed as a promising approach to the making ofa biological tooth (bio-tooth). Dental pulp stem cells(DPSCs) represent a kind of adult cell colony whichhas the potent capacity of self-renewing andmultilineage differentiation. A bio-tooth made fromautogenous DPSCs should be the best choice forclinical tooth reconstruction.