In vitro and in vivo osteogenesis of human mesenchymal stem cells derived from skin, bone marrow and dental follicle tissues

Chemokine‑like receptor 1‑positive cells are present in the odontoblast layer in tooth tissue in rats and humans

Cluster of differentiation (CD)44 is a marker of dental pulp stem cells and is involved in odontoblast differentiation and calcification. Chemokine-like receptor 1 (CMKLR1), also known as chemerin receptor 23 (ChemR23) is also expressed in odontoblasts and dental pulp stem cells and is involved in inflammation suppression and tooth regeneration. Resolvin E1, a bioactive lipid, is a CMKLR1 ligand that mediates the chemerin-CMKLR1 interaction and suppresses pulpal inflammation. The present study clarified the intracellular and tissue localization of CD44 and CMKLR1 by immunohistochemical staining of normal pulp and pulp with pulpitis from 12-week-old male Wistar rat teeth or human teeth. In addition, the localization of CD44 and CMKLR1 in human dental pulp stem cells was observed by immunofluorescence staining. The present study also examined the involvement of resolvin E1 in inhibiting inflammation and calcification by western blotting. CD44- and CMKLR1-positive cells were confirmed in the odontoblast layer in normal dental pulp of rats and humans. CD44 was mainly localized in the cell membrane and CMKLR1 was mainly found in the cytoplasm of human dental pulp stem cells. CMKLR1 was also confirmed in the odontoblast layer in rats and humans with pulpitis but CD44 was not present. Following treatment of dental pulp stem cells with lipoteichoic acid, which imitates Gram-positive bacterial infection, resolvin E1 did not suppress the expression of cyclooxygenase-2 or of the odontoblast differentiation marker, dentin sialophosphoprotein. Furthermore, resolvin E1 induced the differentiation of dental pulp stem cells into odontoblasts even in the presence of the inflammatory stimulus.

Development of photoreactive demineralized bone matrix 3D printing colloidal inks for bone tissue engineering

Demineralized bone matrix (DBM) has been widely used clinically for dental, craniofacial and skeletal bone repair, as an osteoinductive and osteoconductive material. 3D printing (3DP) enables the creation of bone tissue engineering scaffolds with complex geometries and porosity. Photoreactive methacryloylated gelatin nanoparticles (GNP-MAs) 3DP inks have been developed, which display gel-like behavior for high print fidelity and are capable of post-printing photocrosslinking for control of scaffold swelling and degradation. Here, novel DBM nanoparticles (DBM-NPs, ∼400 nm) were fabricated and characterized prior to incorporation in 3DP inks. The objectives of this study were to determine how these DBM-NPs would influence the printability of composite colloidal 3DP inks, assess the impact of ultraviolet (UV) crosslinking on 3DP scaffold swelling and degradation and evaluate the osteogenic potential of DBM-NP-containing composite colloidal scaffolds. The addition of methacryloylated DBM-NPs (DBM-NP-MAs) to composite colloidal inks (100:0, 95:5 and 75:25 GNP-MA:DBM-NP-MA) did not significantly impact the rheological properties associated with printability, such as viscosity and shear recovery or photocrosslinking. UV crosslinking with a UV dosage of 3 J/cm2 directly impacted the rate of 3DP scaffold swelling for all GNP-MA:DBM-NP-MA ratios with an ∼40% greater increase in scaffold area and pore area in uncrosslinked versus photocrosslinked scaffolds over 21 days in phosphate-buffered saline (PBS). Likewise, degradation (hydrolytic and enzymatic) over 21 days for all DBM-NP-MA content groups was significantly decreased, ∼45% less in PBS and collagenase-containing PBS, in UV-crosslinked versus uncrosslinked groups. The incorporation of DBM-NP-MAs into scaffolds decreased mass loss compared to GNP-MA-only scaffolds during collagenase degradation. An in vitro osteogenic study with bone marrow-derived mesenchymal stem cells demonstrated osteoconductive properties of 3DP scaffolds for the DBM-NP-MA contents examined. The creation of photoreactive DBM-NP-MAs and their application in 3DP provide a platform for the development of ECM-derived colloidal materials and tailored control of biochemical cue presentation with broad tissue engineering applications.

LncRNA HOTAIRM1 promotes dental follicle stem cell-mediated bone regeneration by regulating HIF-1α/KDM6/EZH2/H3K27me3 axis

Large bone defect reconstruction undergoes hypoxia and remains a major practical challenge. Bone tissue engineering with a more promising stem cell source facilitates the development of better therapeutic outcomes. Human dental follicle stem cells (hDFSCs) with superior multipotency, osteogenic capacity, and accessibility have been proven a promising cell source for bone regeneration. We previously identified a novel long noncoding RNA (lncRNA), HOTAIRM1, to be highly expressed in hDFSCs. Here we found that HOTAIRM1 overexpressed hDFSCs promoted bone regeneration in rat critical-size calvarial defect model. Mechanically, HOTAIRM1 was induced in hDFSCs under hypoxic conditions and activated HIF-1α. RNA-sequencing analysis indicated that HOTAIRM1 upregulated oxygen-sensing histone demethylases KDM6A/B and suppressed methyltransferase EZH2 via targeting HIF-1α. The osteogenic differentiation of hDFSCs was accompanied with demethylation of H3K27, and HOTAIRM1 overexpression decreased the distribution of H3K27me3 in osteogenic genes, including ALP, M-CSF, Wnt-3a, Wnt-5a, Wnt-7a, and β-catenin, thus promoted their transcription. Our study provided evidence that HOTAIRM1 upregulated KDM6A/B and inhibited EZH2 in a HIF-1α dependent manner to enhance the osteogenesis of hDFSCs. HOTAIRM1-mediated hDFSCs may serve as a promising therapeutic approach to promote bone regeneration in clinical practice.

Tiron Has Negative Effects on Osteogenic Differentiation via Mitochondrial Dysfunction in Human Periosteum-Derived Cells

Tiron is a potent antioxidant that counters the pathological effects of reactive oxygen species (ROS) production due to oxidative stress in various cell types. We examined the effects of tiron on mitochondrial function and osteoblastic differentiation in human periosteum-derived cells (hPDCs). Tiron increased mitochondrial activity and decreased senescence-associated β-galactosidase activity in hPDCs; however, it had a detrimental effect on osteoblastic differentiation by reducing alkaline phosphatase (ALP) activity and alizarin red-positive mineralization, regardless of H₂O₂ treatment. Osteoblast-differentiating hPDCs displayed increased ROS production compared with non-differentiating hPDCs, and treatment with tiron reduced ROS production in the differentiating cells. Antioxidants decreased the rates of oxygen consumption and ATP production, which are increased in hPDCs during osteoblastic differentiation. In addition, treatment with tiron reduced the levels of most mitochondrial proteins, which are increased in hPDCs during culture in osteogenic induction medium. These results suggest that tiron exerts negative effects on the osteoblastic differentiation of hPDCs by causing mitochondrial dysfunction.

Stem Cell Applications in Periodontal Regeneration

In this review, the authors consider the substantial advances that have been made in recent years in stem cell-based periodontal regeneration. These advances involve identifying dental- and nondental-derived stem cells with the capacity to modulate periodontal regeneration, human clinical trials, and emerging concepts, including cell banking, good manufacturing processes, and overall clinical translation.

Sinking Our Teeth in Getting Dental Stem Cells to Clinics for Bone Regeneration

Dental stem cells have been isolated from the medical waste of various dental tissues. They have been characterized by numerous markers, which are evaluated herein and differentiated into multiple cell types. They can also be used to generate cell lines and iPSCs for long-term in vitro research. Methods for utilizing these stem cells including cellular systems such as organoids or cell sheets, cell-free systems such as exosomes, and scaffold-based approaches with and without drug release concepts are reported in this review and presented with new pictures for clarification. These in vitro applications can be deployed in disease modeling and subsequent pharmaceutical research and also pave the way for tissue regeneration. The main focus herein is on the potential of dental stem cells for hard tissue regeneration, especially bone, by evaluating their potential for osteogenesis and angiogenesis, and the regulation of these two processes by growth factors and environmental stimulators. Current in vitro and in vivo publications show numerous benefits of using dental stem cells for research purposes and hard tissue regeneration. However, only a few clinical trials currently exist. The goal of this review is to pinpoint this imbalance and encourage scientists to pick up this research and proceed one step further to translation.

Effects of rhBMP-2 on Bone Formation Capacity of Rat Dental Stem/Progenitor Cells from Dental Follicle and Alveolar Bone Marrow

Dental stem/progenitor cells are a promising cell sources for alveolar bone (AB) regeneration because of their same embryonic origin and superior osteogenic potential. However, their molecular processes during osteogenic differentiation remain unclear. The objective of this study was to identify the responsiveness of dental follicle cells (DFCs) and AB marrow-derived mesenchymal stem cells (ABM-MSCs) to recombinant human bone morphogenetic protein-2 (rhBMP-2). These cells expressed vimentin and MSC markers and did not express cytokeratin and hematopoietic stem cell markers and showed multilineage differentiation potential under specific culture conditions. DFCs exhibited higher proliferation and colony-forming unit-fibroblast efficiency than ABM-MSCs; rhBMP-2 induced DFCs to differentiate toward a cementoblast/osteoblast phenotype and ABM-MSCs to differentiate only toward a osteoblast phenotype; and rhBMP-2-induced DFCs exhibited higher osteogenic differentiation potential than ABM-MSCs. These cells adhered, grew, and produced extracellular matrix on nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA). During a 14-day culture on nHAC/PLA, the extracellular alkaline phosphatase (ALP) activity of DFCs decreased gradually and that of ABM-MSCs increased gradually; rhBMP-2 enhanced their extracellular ALP activity, intracellular osteocalcin (OCN), and osteopontin (OPN) protein expression; and DFCs exhibited higher extracellular ALP activity and intracellular OCN protein expression than ABM-MSCs. When implanted subcutaneously in severe combined immunodeficient mice for 3 months, DFCs+nHAC/PLA+rhBMP-2 obtained higher percentage of bone formation area, OCN, and cementum attachment protein expression and lower OPN expression than ABM-MSCs+nHAC/PLA+rhBMP-2. These results showed that DFCs possessed superior proliferation and osteogenic differentiation potential in vitro, and formed higher quantity and quality bones in vivo. It suggested that DFCs might exhibit a more sensitive responsiveness to rhBMP-2, so that DFCs enter a relatively mature stage of osteogenic differentiation earlier than ABM-MSCs after rhBMP-2 induction. The findings imply that these dental stem/progenitor cells are alternative sources for AB engineering in regenerative medicine, and developing dental tissue may provide better source for stem/progenitor cells.

Evaluation of odonto/osteogenic differentiation potential from different regions derived dental tissue stem cells and effect of 17β-estradiol on efficiency

Background

The dentin is a tissue, which is formed by odontoblasts at the pulp interface of the teeth that supports the enamel. Odontoblasts, the cranial neural crest cells are derived from ectodermal mesenchymal stem cells (MSCs) and are long and polarized cells. They are present at the outer surface of dentin and play a prominent role about dentin formation. Recently, attention has been focused on induction of odontoblast using various type of MSCs and effects of the 17ß-estradiol supplementation. In this study, we establish an efficient odonto/osteoblast differentiation protocol using 17ß-estradiol supplementation while comparing the odonto/osteoblast ability of various dental MSCs.

Methods

Same donor derived four types of dental MSCs namely dental pulp stem cells (DPSCs), stem cells from apical papilla (SCAP), dental follicle stem cells (DFSCs), and periodontal ligament stem cells (PDLSCs) were evaluated for their stemness characteristics and potency towards odonto/osteoblast (Induced odonto/osteoblast) differentiation. Then 17ß-estradiol supplementation of 0 and 10 µM was applied to the odonto/osteoblast differentiation media for 14 days respectively. Furthermore, mRNA and protein levels of odonto/osteoblast markers were evaluated.

Results

All of the experimental groups displayed stemness characteristics by showing adipocyte and chondrocyte differentiation abilities, expression for cell surface markers and cell proliferation capacity without any significant differences. Moreover, all dental derived MSCs were shown to have odonto/osteoblast differentiation ability when cultured under specific conditions and also showed positive expression for odontoblast markers at both mRNA and protein level. Among all, DPSCs revealed the higher differentiation potential than other dental MSCs. Furthermore, odonto/osteoblast differentiation potential was enhanced by supplementing the differentiation media with 17ß-estradiol (E2).

Conclusions

Thus, DPSCs possess higher odonto/osteogenic potential than the SCAPs, DFSCs, PDLSCs and their differentiation capacity can by further enhanced under E2 supplementation.

STRO-1 positive cell expansion during osteogenic differentiation: A comparative study of three mesenchymal stem cell types of dental origin

OBJECTIVE

Although the osteogenic differentiation potential of mesenchymal stem cells of dental origin is well established, the roles of different marker proteins in this process remain to be clarified. Our aim was to compare the cellular and molecular changes, focusing in particular on mesenchymal stem cell markers, during in vitro osteogenesis in three dental stem cell types: dental follicle stem cells (DFSCs), periodontal ligament stem cells (PDLSCs) and dental pulp stem cells (DPSCs).

DESIGN

Human DFSCs, PDLSCs and DPSCs were isolated, cultured and their osteogenic differentiation was induced for 3 weeks. Mineralization was assessed by von Kossa staining and calcium concentration measurements. The expression of mesenchymal and osteogenic markers was studied by immunocytochemistry and qPCR techniques. Alkaline phosphatase (ALP) activity and the frequency of STRO-1 positive cells were also quantified.

RESULTS

The three cultures all showed abundant mineralization, with high calcium content by day 21. The expression of vimentin and nestin was sustained after osteogenic induction. The osteogenic medium induced a considerable elevation of STRO-1 positive cells. By day 7, the ALP mRNA level had increased more than 100-fold in DFSCs, PDLSCs, and DPSCs. Quantitative PCR results indicated dissimilarities of osteoblastic marker levels in the three dental stem cell cultures.

CONCLUSIONS

DFSCs, PDLSCs and DPSCs have similar functional osteogenic differentiation capacities although their expressional profiles of key osteogenic markers show considerable variations. The STRO-1 positive cell fraction expands during osteogenic differentiation while vimentin and nestin expression remain high. For identification of stemness, functional studies rather than marker expressions are needed.

Hepatogenic Potential and Liver Regeneration Effect of Human Liver-derived Mesenchymal-Like Stem Cells

Human liver-derived stem cells (hLD-SCs) have been proposed as a possible resource for stem cell therapy in patients with irreversible liver diseases. However, it is not known whether liver resident hLD-SCs can differentiate toward a hepatic fate better than mesenchymal stem cells (MSCs) obtained from other origins. In this study, we compared the differentiation ability and regeneration potency of hLD-SCs with those of human umbilical cord matrix-derived stem cells (hUC-MSCs) by inducing hepatic differentiation. Undifferentiated hLD-SCs expressed relatively high levels of endoderm-related markers (GATA4 and FOXA1). During directed hepatic differentiation supported by two small molecules (Fasudil and 5-azacytidine), hLD-SCs presented more advanced mitochondrial respiration compared to hUC-MSCs. Moreover, hLD-SCs featured higher numbers of hepatic progenitor cell markers on day 14 of differentiation (CPM and CD133) and matured into hepatocyte-like cells by day 7 through 21 with increased hepatocyte markers (ALB, HNF4A, and AFP). During in vivo cell transplantation, hLD-SCs migrated into the liver of ischemia-reperfusion injury-induced mice within 2 h and relieved liver injury. In the thioacetamide (TAA)-induced liver injury mouse model, transplanted hLD-SCs trafficked into the liver and spontaneously matured into hepatocyte-like cells within 14 days. These results collectively suggest that hLD-SCs hold greater hepatogenic potential, and hepatic differentiation-induced hLD-SCs may be a promising source of stem cells for liver regeneration.

Bromodomain Protein BRD4 Accelerates Glucocorticoid Dysregulation of Bone Mass and Marrow Adiposis by Modulating H3K9 and Foxp1

Glucocorticoid provokes bone mass loss and fatty marrow, accelerating osteoporosis development. Bromodomain protein BRD4, an acetyl–histone-binding chromatin reader, regulates stem cell and tissue homeostasis. We uncovered that glucocorticoid inhibited acetyl Lys-9 at the histone 3 (H3K9ac)-binding Runx2 promoter and decreased osteogenic differentiation, whereas bromodomain protein 4 (BRD4) and adipocyte formation were upregulated in bone-marrow mesenchymal progenitor cells. BRD4 knockdown improved H3K9ac occupation at the Runx2 promoter and osteogenesis, but attenuated glucocorticoid-mediated adipocyte formation together with the unaffected H3K9ac-binding PPARγ2 promoter. BRD4 regulated epigenome related to fatty acid metabolism and the forkhead box P1 (Foxp1) pathway, which occupied the PPARγ2 promoter to modulate glucocorticoid-induced adipocytic activity. In vivo, BRD4 inhibitor JQ-1 treatment mitigated methylprednisolone-induced suppression of bone mass, trabecular microstructure, mineral acquisition, and osteogenic differentiation. Foxp1 signaling, marrow fat, and adipocyte formation in glucocorticoid-treated skeleton were reversed upon JQ-1 treatment. Taken together, glucocorticoid-induced H3K9 hypoacetylation augmented BRD4 action to Foxp1, which steered mesenchymal progenitor cells toward adipocytes at the cost of osteogenic differentiation in osteoporotic skeletons. BRD4 inhibition slowed bone mass loss and marrow adiposity. Collective investigations convey a new epigenetic insight into acetyl histone reader BRD4 control of osteogenesis and adipogenesis in skeleton, and highlight the remedial effects of the BRD4 inhibitor on glucocorticoid-induced osteoporosis.

Skin-derived precursor Schwann cells protect SH-SY5Y cells against 6-OHDA-induced neurotoxicity by PI3K/AKT/Bcl-2 pathway

Skin-derived precursors (SKPs) are self-renewing and pluripotent adult stem cell sources that have been successfully obtained and cultured from adult tissues of rodents and humans. Skin-derived precursor Schwann cells (SKP-SCs), derived from SKPs when cultured in a neuro stromal medium supplemented with some appropriate neurotrophic factors, have been reported to play a neuroprotective effect in the peripheral nervous system. This proves our previous studies that SKP-SCs' function to bridge sciatic nerve gap in rats. However, the function of SKP-SCs in Parkinson disease (PD) remains unknown. This study was aimed to investigate the possible neuroprotective effects of SKP-SCs in 6-OHDA-induced Parkinson's disease (PD) model. Our results showed that the treatment with SKP-SCs prevented SH-SY5Y cells from 6-OHDA-induced apoptosis, accompanied by modulation of apoptosis-related proteins (Bcl-2 and Bax) and the decreased expression of active caspase-3. Furthermore, we confirmed that SKP-SCs might exert protective effects and increase the mitochondrial membrane potential (MMP) through PI3K/AKT/Bcl-2 pathway. Taken together, our results demonstrated that SKP-SCs protect against 6-OHDA-induced cytotoxicity through PI3K/AKT/Bcl-2 pathway in PD model in vitro, which provides a new theoretical basis for the treatment of PD.

Mitochondrial genome mutations in mesenchymal stem cells derived from human dental induced pluripotent stem cells

Ethical and safety issues have rendered mesenchymal stem cells (MSCs) popular candidates in regenerative medicine, but their therapeutic capacity is lower than that of induced pluripotent stem cells (iPSCs). This study compared original, dental tissue-derived MSCs with re-differentiated MSCs from iPSCs (iPS-MSCs). CD marker expression in iPS-MSCs was similar to original MSCs. iPS-MSCs expressed higher in pluripotent genes, but lower levels in mesodermal genes than MSCs. In addition, iPS-MSCs did not form teratomas. All iPSCs carried mtDNA mutations; some shared with original MSCs and others not previously detected therein. Shared mutations were synonymous, while novel mutations were non-synonymous or located on RNA-encoding genes. iPS-MSCs also harbored mtDNA mutations transmitted from iPSCs. Selected iPS-MSCs displayed lower mitochondrial respiration than original MSCs. In conclusion, screening for mtDNA mutations in iPSC lines for iPS-MSCs can identify mutation-free cell lines for therapeutic applications. [BMB Reports 2019; 52(12): 689-694].

Aminated 3D Printed Polystyrene Maintains Stem Cell Proliferation and Osteogenic Differentiation

As 3D printing becomes more common and the technique is used to build culture platforms, it is imperative to develop surface treatments for specific responses. The advantages of aminating and oxidizing polystyrene (PS) for human mesenchymal stem cell (hMSC) proliferation and osteogenic differentiation are investigated. We find that ammonia (NH3) plasma incorporates amines while oxygen plasma adds carbonyl and carboxylate groups. Across 2D, 3D, and 3D dynamic culture, we find that the NH3- treated surfaces encouraged cell proliferation. Our results show that the NH3-treated scaffold was the only treatment allowing dynamic proliferation of hMSCs with little evidence of osteogenic differentiation. With osteogenic media, particularly in 3D culture, we find the NH3 treatment encouraged greater and earlier expression of RUNX2 and ALP. The NH3-treated PS scaffolds support hMSC proliferation without spontaneous osteogenic differentiation in static and dynamic culture. This work provides an opportunity for further investigations into shear profiling and coculture within the developed culture system toward developing a bone marrow niche model.

Mesenchymal stem cells and biologic factors leading to bone formation

BACKGROUND

Physiological bone formation and bone regeneration occurring during bone repair can be considered distinct but similar processes. Mesenchymal stem cells (MSC) and associated biologic factors are crucial to both bone formation and bone regeneration.

AIM

To perform a narrative review of the current literature regarding the role of MSC and biologic factors in bone formation with the aim of discussing the clinical relevance of in vitro and in vivo animal studies.

METHODS

The literature was searched for studies on MSC and biologic factors associated with the formation of bone in the mandible and maxilla. The search specifically targeted studies on key aspects of how stem cells and biologic factors are important in bone formation and how this might be relevant to bone regeneration. The results are summarized in a narrative review format.

RESULTS

Different types of MSC and many biologic factors are associated with bone formation in the maxilla and mandible.

CONCLUSION

Bone formation and regeneration involve very complex and highly regulated cellular and molecular processes. By studying these processes, new clinical opportunities will arise for therapeutic bone regenerative treatments.

Therapeutic effect of mesenchymal stem cells derived from human umbilical cord in rabbit temporomandibular joint model of osteoarthritis

Osteoarthritis (OA) is a degenerative condition of the temporomandibular joint (TMJ) characterised by chronic inflammation and damage to joint structures. Because of the complexity of TMJ-OA, only symptomatic treatments are currently available. Recent reports have shown that many of stem cells can exert anti-inflammatory and tissue-regenerating effects. In this study, we investigated the potential cartilage-regenerating and anti-inflammatory effects of human umbilical cord matrix-mesenchymal stem cells (hUCM-MSCs) for the treatment of TMJ-OA. hUCM-MSC lines, isolated from different donors, which showed different activities in vitro. Using a selected cell line, we used different concentrations of hUCM-MSCs to assess therapeutic effects in a rabbit model of monosodium iodoacetate-induced TMJ-OA. Compared with the untreated control group, the potential regenerative result and anti-inflammatory effects of hUCM-MSCs were evident at all the tested concentrations in rabbits with induced TMJ-OA. The median dose of hUCM-MSCs showed the prominent cartilage protective effect and further cartilage regeneration potential. This effect occurred via upregulated expression of growth factors, extracellular matrix markers, and anti-inflammatory cytokines, and reduced expression of pro-inflammatory cytokines. The anti-inflammatory effect of hUCM-MSCs was comparable to that of dexamethasone (DEX). However, only hUCM-MSCs showed potential chondrogenesis effects in this study. In conclusion, our results indicate that hUCM-MSCs may be an effective treatment option for the treatment of TMJ-OA.

Three-Dimensional Spheroid Formation of Cryopreserved Human Dental Follicle-Derived Stem Cells Enhances Pluripotency and Osteogenic Induction Properties

Background

Enhancement and maintenance of the stemness of mesenchymal stem cells (MSCs) is one of the most important factors contributing to the successful in vivo therapeutic application of these cells. In this regard, three-dimensional (3D) spheroid formation has been developed as reliable method for increasing the pluripotency of MSCs. Moreover, using a new protocol, we have previously shown that dental tissues of extracted wisdom teeth can be effectively cryopreserved for subsequent use as a source of autologous stem cells. The main purpose of this study is to analyze the stemness and in vitro osteogenic differentiation potential of 3D spheroid dental MSCs compared with conventional mono-layer cultured MSCs.

Methods

In this study, MSC-characterized stem cells were isolated and cultured from long-term cryopreserved dental follicles (hDFSCs), and then 2D hDFSCs were cultured under 3D spheroid-forming conditions using a newly designed microchip dish. The spheroids (3D hDFSCs) thus produced were investigated and characterized with respect to stemness, MSC marker expression, apoptosis, cell cycle analysis, extracellular matrix (ECM) production, and osteogenic and adipogenic differentiation properties.

Results

In terms of MSC and senescence markers, spheroid cells showed no difference when compared with 2D hDFSCs; however, 3D hDFSCs were observed to have a higher proportion of cell cycle arrest and a larger number of apoptotic cells. Moreover, spheroids showed substantially increased levels of pluripotency marker (early transcription factors) and ECM protein expression. Compared with 2D hDFSCs, there was also a notable enhancement in the osteogenic induction potential of spheroids, although no differences were observed with respect to in vitro adipogenesis.

Conclusion

To the best of our knowledge, this is the first study to demonstrate the application of a spheroid culture system for dental follicle-derived stem cells using a microchip dish. Although further studies are needed, including in vivo transplantation, the results obtained in this study indicate that spheroid hDFSCs derived from cryopreserved dental follicle tissues could be used as a valuable source of autologous stem cells for bone tissue regeneration.

NFIC promotes the vitality and osteogenic differentiation of rat dental follicle cells

Nuclear factor I-C (NFIC) plays critical roles in the regulation of tooth development by influencing the biological behaviors of stem cells in the dental germ. This study aimed to investigate the effect of NFIC on the vitality and osteogenic/cementogenic differentiation of rat dental follicle cells (DFCs). DFCs were isolated from dental follicles in the first molars of neonatal rats. DFCs expressed mesenchymal stromal cell markers CD29, CD44 and CD90 and had capabilities for self-renewal and multipotent differentiation. Overexpression of NFIC promoted the proliferation of DFCs without markedly influencing the apoptosis of DFCs. Moreover, NFIC increased alkaline phosphatase (ALP) activity in DFCs and upregulated the mRNA levels of osteogenic-related markers, namely, collagen type I (Col I), Runt-related transcription factor 2 (Runx2) and ALP, as well as β-catenin. In contrast, silencing NFIC by siRNA increased the apoptosis of DFCs and downregulated the expression of osteogenic-related markers. In conclusion, these results suggested that upregulation of NFIC may promote the proliferation and osteogenic/cementogenic differentiation of DFCs.

An In Vitro Comparative Study of Multisource Derived Human Mesenchymal Stem Cells for Bone Tissue Engineering

Mesenchymal stem cells (MSCs) have been considered promising tools for tissue engineering and regenerative medicine. However, the optimal cell source for bone regeneration remains controversial. To better identify seed cells for bone tissue engineering, we compared MSCs from seven different tissues, including four from dental origins, dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), gingival MSCs (GMSCs), and dental follicle stem cells (DFSCs); two from somatic origins, bone marrow-derived MSCs (BM-MSCs) and adipose-derived stem cells (ADSCs); and one from birth-associated perinatal tissue umbilical cord (UCMSCs). We cultured the cells under a standardized culture condition and studied their biological characteristics. According to our results, these cells exhibited similar immunophenotype and had potential for multilineage differentiation. MSCs from dental and perinatal tissues proliferated more rapidly than those from somatic origins. Simultaneously, DPSCs and PDLSCs owned stronger antiapoptotic ability under the microenvironment of oxidative stress combined with serum deprivation. In respect to osteogenic differentiation, the two somatic MSCs, BM-MSCs and ADSCs, demonstrated the strongest ability for osteogenesis compared to PDLSCs and DFSCs, which were just a little bit weaker than the formers. However, GMSCs and UCMSCs were the most pertinacious ones to differentiate to osteoblasts. We also revealed that the canonical intracellular protein kinase-based cascade signaling pathways, including PI3K/AKT, MAPK/ERK, and p38 MAPK, possessed different levels of activation in different MSCs after osteoblast induction. Our conclusions suggest that PDLSCs might be a good potential alternative to BM-MSCs for bone tissue engineering.

The effect of strontium chloride on human periodontal ligament stem cells

The complete repair of periodontal structures remains an exciting challenge that prompts researchers to develop new treatments to restore the periodontium. Recent research has suggested strontium ion to be an attractive candidate to improve osteogenic activity. In this study, we have isolated a clonal finite cell line derived from human periodontal ligament (PDL) in order to assess whether and in which way different doses of SrCl₂ (from 0.5 to 500 μg/ml) can influence both the proliferation and the mineralization process, for future application in oral diseases. PDL cells were cloned by dilution plating technique and characterized by FACS. Cell proliferation analysis and mineralization were performed by [³H]-thymidine incorporation and spectrofluorometric assay. Results have evidenced that the higher SrCl₂ concentrations tested, from 25 to 500 μg/ml, have increased the proliferation activity after only 24 h of treatment. Interestingly, the same higher concentrations have decreased the mineralization, which was conversely increased by the lower ones, from 0.5 to 10 μg/ml. Our findings suggest the possible use of SrCl₂ in appropriate delivery systems that release, at different time points, the specific dose, depending on the biological response that we want to induce on periodontal ligament stem cells, providing a more efficient periodontal regeneration.

Dental Stem Cells in Bone Tissue Engineering: Current Overview and Challenges

The treatment of bone that is impaired due to disease, trauma or tumor resection creates a challenge for both clinicians and researchers. Critical size bone defects are conventionally treated with autografts which are associated with risks such as donor site morbidity and limitations like donor shortage. Bone tissue engineering has become a promising area for the management of critical size bone defects by the employment of biocompatible materials and the discovery of novel stem cell sources. Mesenchymal stem cells (MSCs) can be isolated with ease from various dental tissues including dental pulp stem cells, stem cells from apical papilla, dental follicle stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, gingival stem cells and tooth germ derived stem cells. Outcomes of dental MSC mediated bone tissue engineering is explored in various in vivo and in vitro preclinical studies. However, there are still obscurities regarding the mechanisms underlying in MSC mediated bone regeneration and challenges in applications of dental stem cells. In this review, we summarized dental stem cell sources and their characterizations, along with currently used biomaterials for cell delivery and future perspectives for dental MSCs in the field of bone tissue engineering. Further efforts are necessary before moving to clinical trials for future applications.

Comparative analysis of molecular activity in dermal mesenchymal stem cells from different passages

Mesenchymal stem cells (MSCs) are used for tissue regeneration in several pathological conditions, including autoimmune diseases. However, the optimal sources and culture requirements for these cells are still under investigation. Here, we compared mRNA expression in dermal MSCs (DMSCs) at passage (P) 3 and P5 to provide a reference for future studies related to DMSCs expansion. In normal DMSCs, the expression of three of eight genes associated with basic cellular activity were different at P5 compared to that at P3: PLCB4 and SYTL2 were upregulated by 4.30- and 6.42-fold, respectively (P < 0.05), whereas SATB2 was downregulated by 39.25-fold (P < 0.05). At the same time, genes associated with proliferation, differentiation, inflammation, and apoptosis were expressed at similar levels at P3 and P5 (P > 0.05). In contrast, in DMSCs isolated from psoriatic patients we observed differential expression of three inflammation-associated genes at P5 compared to P3; thus IL6, IL8, and CXCL6 mRNA levels were upregulated by 16.02-, 31.15-, and 15.04-fold, respectively. Our results indicate that normal and psoriatic DMSCs showed different expression patterns for genes related to inflammation and basic cell activity at P3 and P5, whereas those for genes linked to proliferation, differentiation, and apoptosis were mostly similar.

Adult Stem Cells of Orofacial Origin: Current Knowledge and Limitation and Future Trend in Regenerative Medicine

Stem cell research is one of the most rapidly expanding field of medicine which provides significant opportunities for therapeutic and regenerative applications. Different types of stem cells have been isolated investigating their accessibility, control of the differentiation pathway and additional immunomodulatory properties. Bulk of the literature focus has been on the study and potential applications of adult stem cells (ASC) because of their low immunogenicity and reduced ethical considerations. This review paper summarizes the basic available literature on different types of ASC with special focus on stem cells from dental and orofacial origin. ASC have been isolated from different sources, however, isolation of ASC from orofacial tissues has provided a novel promising alternative. These cells offer a great potential in the future of therapeutic and regenerative medicine because of their remarkable availability at low cost while allowing minimally invasive isolation procedures. Furthermore, their immunomodulatory and anti-inflammatory potential is of particular interest. However, there are conflicting reports in the literature regarding their particular biology and full clinical potentials. Sound knowledge and higher control over proliferation and differentiation mechanisms are prerequisites for clinical applications of these cells. Therefore, further standardized basic and translational studies are required to increase the reproducibility and reduce the controversies of studies, which in turn facilitate comparison of related literature and enhance further development in the field.

* Extracellular Matrices for Bone Regeneration: A Literature Review

The gold standard material for bone regeneration is still autologous bone, a mesenchymal tissue that consists mainly of extracellular matrix (ECM) (90% v/v) and little cellular content (10% v/v). However, the fact that decellularized allogenic bone grafts often present a clinical performance comparable to autologous bone grafts demonstrates the crucial role of ECM in bone regeneration. For long, the mechanism by which bone allografts function was not clear, but recent research has unveiled many unique characteristics of ECM that seem to play a key role in tissue regeneration. This is further confirmed by the fact that synthetic biomaterials with composition and properties resembling bone ECM present excellent bone regeneration properties. In this context, ECM molecules such as glycosaminoglycans (GAGs) and self-assembly peptides (SAPs) can improve the performance of bone regeneration biomaterials. Moreover, decellularized ECM derived either from native tissues such as bone, cartilage, skin, and tooth germs or from cells such as osteoblasts, chondrocytes, and stem cells has shown promising results in bone regeneration applications. Understanding the role of ECM in bone regeneration is crucial for the development of the next generation of biomaterials for bone tissue engineering. In this sense, this review addresses the state-of-the-art on this subject matter.

A review of fibrin and fibrin composites for bone tissue engineering

Tissue engineering has emerged as a new treatment approach for bone repair and regeneration seeking to address limitations associated with current therapies, such as autologous bone grafting. While many bone tissue engineering approaches have traditionally focused on synthetic materials (such as polymers or hydrogels), there has been a lot of excitement surrounding the use of natural materials due to their biologically inspired properties. Fibrin is a natural scaffold formed following tissue injury that initiates hemostasis and provides the initial matrix useful for cell adhesion, migration, proliferation, and differentiation. Fibrin has captured the interest of bone tissue engineers due to its excellent biocompatibility, controllable biodegradability, and ability to deliver cells and biomolecules. Fibrin is particularly appealing because its precursors, fibrinogen, and thrombin, which can be derived from the patient's own blood, enable the fabrication of completely autologous scaffolds. In this article, we highlight the unique properties of fibrin as a scaffolding material to treat bone defects. Moreover, we emphasize its role in bone tissue engineering nanocomposites where approaches further emulate the natural nanostructured features of bone when using fibrin and other nanomaterials. We also review the preparation methods of fibrin glue and then discuss a wide range of fibrin applications in bone tissue engineering. These include the delivery of cells and/or biomolecules to a defect site, distributing cells, and/or growth factors throughout other pre-formed scaffolds and enhancing the physical as well as biological properties of other biomaterials. Thoughts on the future direction of fibrin research for bone tissue engineering are also presented. In the future, the development of fibrin precursors as recombinant proteins will solve problems associated with using multiple or single-donor fibrin glue, and the combination of nanomaterials that allow for the incorporation of biomolecules with fibrin will significantly improve the efficacy of fibrin for numerous bone tissue engineering applications.

The Characteristics Of Human Bone-Derived Cells (HBDCS) during osteogenesis in vitro

BACKGROUND

The primary human bone-derived cell culture technique is used as a model to study human osteogenesis. Compared to cell line cultures, primary osteoprogenitor and osteoblast cultures provide more complex information about osteogenesis, bone remodeling and regeneration than cell line cultures.

METHODS

In this study, we isolated human bone-derived cells (HBDCs) and promoted their differentiation into osteoblasts. The following parameters were evaluated: cell number and viability, total protein expression, alkaline phosphatase activity, collagenous matrix production and osteogenic genes expression, i.e., gene coding for type I collagen and alkaline phosphatase.

RESULTS

It was proved the results show that HBDCs intensively proliferate during the first 7 days of culture followed by differentiation accompanied by an increase in alkaline phosphatase activity. Moreover, it was observed that during the differentiation of HBDCs, the expression of integrin β1 increased.

CONCLUSIONS

The process was also accompanied by changes in cell shape and rearrangement of the actin cytoskeleton and focal contacts containing FAK and the integrin β1 subunit. We suggest that the β1 integrin subunit may be a suitable new target in studies of the differentiation of primary human osteoblasts in culture.

In vitro comparative analysis of human dental stem cells from a single donor and its neuronal differentiation potential evaluated by electrophysiology

AIMS

The aim of this study was to find out a mesenchymal stem cells (MSCs) source from human dental tissues of the same donor (follicle, papilla and pulp), which exhibits higher neurogenic differentiation potential in vitro.

MAIN METHODS

MSCs were isolated from dental tissues (follicle, papilla and pulp) by digestion method. All MSCs were analyzed for pluripotent makers by western blot, cell surface markers by flow cytometry, adipo- and osteocytes markers by RT-qPCR. The neuronal differentiated MSCs were characterized for neuronal specific markers by RT-qPCR and immunofluorescence. Functional neuronal properties were analyzed by electrophysiology and synaptic markers expression.

KEY FINDINGS

All MSCs expressed pluripotent markers (Oct4, Sox2 and Nanog) and were found positive for mesenymal markers (CD44, CD90, CD105) while negative for hematopoietic markers (CD34 and CD45). Furthermore, MSCs were successfully differentiated into adipocytes, osteocytes and trans-differentiated into neuronal cells. Among them, dental pulp derived MSCs exhibits higher neurogenic differentiation potential, in term of expression of neuronal specific markers at both gene and protein level, and having higher Na(+) and K(+) current with the expression of synaptic markers.

SIGNIFICANCE

The three types of dental MSCs from a single donor broadly possessed similar cellular properties and can differentiate into neuronal cells; however, pulp derived MSCs showed higher neurogenic potential than the follicle and papilla, suggesting their use in future stem cells therapy for the treatment of neurodegenerative disorders.

A comparison of commercially available demineralized bone matrices with and without human mesenchymal stem cells in a rodent spinal fusion model

OBJECTIVE The efficacy of some demineralized bone matrix (DBM) substances has been demonstrated in the spinal fusion of rats; however, no previous comparative study has reported the efficacy of DBM with human mesenchymal stem cells (hMSCs). There is an added cost to the products with stem cells, which should be justified by improved osteogenic potential. The purpose of this study is to prospectively compare the fusion rates of 3 different commercially available DBM substances, both with and without hMSCs. METHODS Posterolateral fusion was performed in 32 mature athymic nude rats. Three groups of 8 rats were implanted with 1 of 3 DBMs: Trinity Evolution (DBM with stem cells), Grafton (DBM without stem cells), or DBX (DBM without stem cells). A fourth group with no implanted material was used as a control group. Radiographs were obtained at 2, 4, and 8 weeks. The rats were euthanized at 8 weeks. Overall fusion was determined by manual palpation and micro-CT. RESULTS The fusion rates at 8 weeks on the radiographs for Trinity Evolution, Grafton, and DBX were 8 of 8 rats, 3 of 8 rats, and 5 of 8 rats, respectively. A significant difference was found between Trinity Evolution and Grafton (p = 0.01). The overall fusion rates as determined by micro-CT and manual palpation for Trinity Evolution, Grafton, and DBX were 4 of 8 rats, 3 of 8 rats, and 3 of 8 rats, respectively. The Trinity Evolution substance had the highest overall fusion rate, however no significant difference was found between groups. CONCLUSIONS The efficacies of these DBM substances are demonstrated; however, the advantage of DBM with hMSCs could not be found in terms of posterolateral fusion. When evaluating spinal fusion using DBM substances, CT analysis is necessary in order to not overestimate fusion.

Cardiomyogenic Differentiation of Human Dental Follicle-derived Stem Cells by Suberoylanilide Hydroxamic Acid and Their In Vivo Homing Property

The purpose of the present study was to investigate the in vitro cardiomyogenic differentiation potential of human dental follicle-derived stem cells (DFCs) under the influence of suberoylanilide hydroxamic acid (SAHA), a member of the histone deacetylase inhibitor family, and analyze the in vivo homing capacity of induced cardiomyocytes (iCMs) when transplanted systemically. DFCs from extracted wisdom teeth showed mesenchymal stem cell (MSC) characteristics such as plate adherent growing, expression of MSC markers (CD44, CD90, and CD105), and mesenchymal lineage-specific differentiation potential. Adding SAHA to the culture medium induced the successful in vitro differentiation of DFCs into cardiomyocytes. These iCMs expressed cardiomyogenic markers, including alpha-smooth muscle actin (α-SMA), cardiac muscle troponin T (TNNT2), Desmin, and cardiac muscle alpha actin (ACTC1), at both the mRNA and protein level. For the assessment of homing capacity, PKH26 labeled iCMs were intraperitoneally injected (1×10⁶ cells in 100 µL of PBS) into the experimental mice, and the ratios of PKH26 positive cells to the total number of injected cells, in multiple organs were determined. The calculated homing ratios, 14 days after systemic cell transplantation, were 5.6 ± 1.0%, 3.6 ± 1.1%, and 11.6 ± 2.7% in heart, liver, and kidney respectively. There was no difference in the serum levels of interleukin-2 and interleukin-10 at 14 days after transplantation, between the experimental (iCM injected) and control (no injection or PBS injection) groups. These results demonstrate that DFCs can be an excellent source for cardiomyocyte differentiation and regeneration. Moreover, the iCMs can be delivered into heart muscle via systemic administration without eliciting inflammatory or immune response. This can serve as the pilot study for further investigations into the in vitro cardiomyogenic differentiation potential of DFCs under the influence of SAHA and the in vivo homing capacity of the iCMs into the heart muscle, when injected systemically.

Immunomodulatory properties and in vivo osteogenesis of human dental stem cells from fresh and cryopreserved dental follicles

In our previous study, dental follicle tissues from extracted wisdom teeth were successfully cryopreserved for use as a source of stem cells. The goals of the present study were to investigate the immunomodulatory properties of stem cells from fresh and cryopreserved dental follicles (fDFCs and cDFCs, respectively) and to analyze in vivo osteogenesis after transplantation of these DFCs into experimental animals. Third passage fDFCs and cDFCs showed similar expression levels of interferon-γ receptor (CD119) and major histocompatibility complex class I and II (MHC I and MHC II, respectively), with high levels of CD119 and MHC I and nearly no expression of MHC II. Both fresh and cryopreserved human DFCs (hDFCs) were in vivo transplanted along with a demineralized bone matrix scaffold into mandibular defects in miniature pigs and subcutaneous tissues of mice. Radiological and histological evaluations of in vivo osteogenesis in hDFC-transplanted sites revealed significantly enhanced new bone formation activities compared with those in scaffold-only implanted control sites. Interestingly, at 8 weeks post-hDFC transplantation, the newly generated bones were overgrown compared to the original size of the mandibular defects, and strong expression of osteocalcin and vascular endothelial growth factor were detected in the hDFCs-transplanted tissues of both animals. Immunohistochemical analysis of CD3, CD4, and CD8 in the ectopic bone formation sites of mice showed significantly decreased CD4 expression in DFCs-implanted tissues compared with those in control sites. These findings indicate that hDFCs possess immunomodulatory properties that involved inhibition of the adaptive immune response mediated by CD4 and MHC II, which highlights the usefulness of hDFCs in tissue engineering. In particular, long-term preserved dental follicles could serve as an excellent autologous or allogenic stem cell source for bone tissue regeneration as well as a valuable therapeutic agent for immune diseases.

Cell-Mediated Dexamethasone Release from Semi-IPNs Stimulates Osteogenic Differentiation of Encapsulated Mesenchymal Stem Cells

Scaffold-based delivery of bioactive molecules capable of directing stem cell differentiation is critical to the development of point-of-care cell therapy for orthopedic repair. Dexamethasone-conjugated hyaluronic acid (HA-DXM) was synthesized and combined with hydrolytically degradable, photo-cross-linkable PEG-bis(2-acryloyloxy propanoate) (PEG-bis-AP) to form semi-IPNs. Dexamethasone (DX) release was limited in physiological buffer and substantially increased in the presence of encapsulated human mesenchymal stem cells (hMSCs) or exogenous hyaluronidase, confirming that release occurred primarily by a cell-mediated enzymatic mechanism. hMSCs encapsulated in PEG-bis-AP/HA-DXM semi-IPNs increased osteoblast-specific gene expression, alkaline phosphatase activity, and matrix mineralization, attaining levels that were not significantly different from positive controls consisting of hMSCs in PEG-bis-AP/native HA cultured with DX supplementation in the culture medium. These studies demonstrate that PEG-bis-AP/HA-DXM semi-IPNs can provide cell-mediated release of bioactive free DX that induces hMSC osteogenic differentiation. This approach offers an efficient system for local delivery of osteogenic molecules empowering point of care applications.

Osteogenic Potential of Dental Mesenchymal Stem Cells in Preclinical Studies: A Systematic Review Using Modified ARRIVE and CONSORT Guidelines

Background and Objective. Dental stem cell-based tissue engineered constructs are emerging as a promising alternative to autologous bone transfer for treating bone defects. The purpose of this review is to systematically assess the preclinical in vivo and in vitro studies which have evaluated the efficacy of dental stem cells on bone regeneration. Methods. A literature search was conducted in Ovid Medline, Embase, PubMed, and Web of Science up to October 2014. Implantation of dental stem cells in animal models for evaluating bone regeneration and/or in vitro studies demonstrating osteogenic potential of dental stem cells were included. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to ensure the quality of the search. Modified ARRIVE (Animal research: reporting in invivo experiments) and CONSORT (Consolidated reporting of trials) were used to critically analyze the selected studies. Results. From 1914 citations, 207 full-text articles were screened and 137 studies were included in this review. Because of the heterogeneity observed in the studies selected, meta-analysis was not possible. Conclusion. Both in vivo and in vitro studies indicate the potential use of dental stem cells in bone regeneration. However well-designed randomized animal trials are needed before moving into clinical trials.

Proteomics approaches for the studies of bone metabolism

Bone is an active tissue, in which bone formation by osteoblast is followed by bone resorption by osteoclasts, in a repeating cycle. Proteomics approaches may allow the detection of changes in cell signal transduction, and the regulatory mechanism of cell differentiation. LC-MS/MS-based quantitative methods can be used with labeling strategies, such as SILAC, iTRAQ, TMT and enzymatic labeling. When used in combination with specific protein enrichment strategies, quantitative proteomics methods can identify various signaling molecules and modulators, and their interacting proteins in bone metabolism, to elucidate biological functions for the newly identified proteins in the cellular context. In this article, we will briefly review recent major advances in the application of proteomics for bone biology, especially from the aspect of cellular signaling. [BMB Reports 2014; 47(3): 141-148]

Neurogenic differentiation from adipose-derived stem cells and application for autologous transplantation in spinal cord injury

Mesenchymal stem cells derived from adipose tissue have the capacity to differentiate into endodermal, mesoderm and ectodermal cell lineages in vitro, which are an ideal engraft in tissue-engineered repair. In this study, mouse adipose-derived stem cells (ADSCs) were isolated from subcutaneous fat. The markers of ADSCs, CD13, CD29, CD44, CD71, CD73, CD90, CD105, CD166, Nestin, GFAP and MAP-2 were detected by immunofluorescence assays. The ADSCs were cultured in cocktail factors (including ATRA, GGF-2, bFGF, PDGF and forskolin) for neurogenic differentiation. The neurogenic cells markers, Nestin, GFAP and MAP-2 were analyzed using immunofluorescence and real-time PCR after dramatic changes in morphology. Neurogenic cells from ADSCs were autologous transplanted into the mouse of spinal cord injury for observation neurogenic cells colonization in spinal cord. The result demonstrated that the mouse ADSCs were positive for the CD13, CD29, CD44, CD71, CD73, CD90, CD105 and CD166 but negative for neurogenic cell markers, MAP-2, GFAP and Nestin. After neurogenic differentiation, the neurogenic cells were positive for neurogenic cell special markers, gene expression level showed a time-lapse increase, and the cells were successful colonized into spinal cord. In conclusion, our research shows that a population of neuronal cells can be specifically generated from ADSCs and that induced cells may allow for participation in tissue-repair.

Cryopreservation of human dental follicle tissue for use as a resource of autologous mesenchymal stem cells

The main purpose of this study was to develop a cryopreservation method for human dental follicle tissue to maintain autologous stem cells as a resource. A modified cryoprotectant, consisting of 0.05 m glucose, 0.05 m sucrose and 1.5 m ethylene glycol in phosphate-buffered saline (PBS) was employed, with a slow-ramp freezing rate. We observed > 70% of cell survival rate after 3 months of tissue storage. Isolated and cultured human dental stem cells (hDSCs) from cryopreserved dental follicles expressed mesenchymal stem cell markers at a level similar to that of hDSCs from fresh tissue. They also successfully differentiated in vitro into the mesenchymal lineage, osteocytes, adipocytes and chondrocytes under specific inductions. Using immunohistochemistry, the early transcription factors OCT4, NANOG and SOX2 were moderately or weakly detected in the nucleus of both fresh and cryopreserved dental follicles. In addition, p63, CCND1, BCL2 and BAX protein expression levels were the same in both fresh and cryopreserved tissues. However, the positive-cell ratio and intensity of p53 protein was higher in cryopreserved tissues than in fresh tissues, indicating direct damage of the freeze-thawing process. Real-time PCR analysis of hDSCs at passage 2 from both fresh and cryopreserved dental follicles showed similar levels of mRNA for apoptosis- and transcription-related genes. Based on these results, a newly developed cryoprotectant, along with a slow ramp rate freezing procedure allows for long-term dental tissue preservation for later use as an autologous stem cell resource in regenerative cell therapy. Copyright © 2014 John Wiley & Sons, Ltd.

Fibrin Sealant: The Only Approved Hemostat, Sealant, and Adhesive-a Laboratory and Clinical Perspective

Background. Fibrin sealant became the first modern era material approved as a hemostat in the United States in 1998. It is the only agent presently approved as a hemostat, sealant, and adhesive by the Food and Drug Administration (FDA). The product is now supplied as patches in addition to the original liquid formulations. Both laboratory and clinical uses of fibrin sealant continue to grow. The new literature on this material also continues to proliferate rapidly (approximately 200 papers/year). Methods. An overview of current fibrin sealant products and their approved uses and a comprehensive PubMed based review of the recent literature (February 2012, through March 2013) on the laboratory and clinical use of fibrin sealant are provided. Product information is organized into sections based on a classification system for commercially available materials. Publications are presented in sections based on both laboratory research and clinical topics are listed in order of decreasing frequency. Results. Fibrin sealant remains useful hemostat, sealant, and adhesive. New formulations and applications continue to be developed. Conclusions. This agent remains clinically important with the recent introduction of new commercially available products. Fibrin sealant has multiple new uses that should result in further improvements in patient care.

Decellularized tissue and cell-derived extracellular matrices as scaffolds for orthopaedic tissue engineering

The reconstruction of musculoskeletal defects is a constant challenge for orthopaedic surgeons. Musculoskeletal injuries such as fractures, chondral lesions, infections and tumor debulking can often lead to large tissue voids requiring reconstruction with tissue grafts. Autografts are currently the gold standard in orthopaedic tissue reconstruction; however, there is a limit to the amount of tissue that can be harvested before compromising the donor site. Tissue engineering strategies using allogeneic or xenogeneic decellularized bone, cartilage, skeletal muscle, tendon and ligament have emerged as promising potential alternative treatment. The extracellular matrix provides a natural scaffold for cell attachment, proliferation and differentiation. Decellularization of in vitro cell-derived matrices can also enable the generation of autologous constructs from tissue specific cells or progenitor cells. Although decellularized bone tissue is widely used clinically in orthopaedic applications, the exciting potential of decellularized cartilage, skeletal muscle, tendon and ligament cell-derived matrices has only recently begun to be explored for ultimate translation to the orthopaedic clinic.

Semaphorin 3A induces mesenchymal-stem-like properties in human periodontal ligament cells

Periodontal ligament stem cells (PDLSCs) have recently been proposed as a novel option in periodontal regenerative therapy. However, one of the issues is the difficulty of stably generating PDLSCs because of the variation of stem cell potential between donors. Here, we show that Semaphorin 3A (Sema3A) can induce mesenchymal-stem-like properties in human periodontal ligament (PDL) cells. Sema3A expression was specifically observed in the dental follicle during tooth development and in parts of mature PDL tissue in rodent tooth and periodontal tissue. Sema3A expression levels were found to be higher in multipotential human PDL cell clones compared with low-differentiation potential clones. Sema3A-overexpressing PDL cells exhibited an enhanced capacity to differentiate into both functional osteoblasts and adipocytes. Moreover, PDL cells treated with Sema3A only at the initiation of culture stimulated osteogenesis, while Sema3A treatment throughout the culture had no effect on osteogenic differentiation. Finally, Sema3A-overexpressing PDL cells upregulated the expression of embryonic stem cell markers (NANOG, OCT4, and E-cadherin) and mesenchymal stem cell markers (CD73, CD90, CD105, CD146, and CD166), and Sema3A promoted cell division activity of PDL cells. These results suggest that Sema3A may possess the function to convert PDL cells into mesenchymal-stem-like cells.