Characterization of stem cells from the pulp of unerupted third molar tooth.

CONTEXT: Dental pulp stem cells (DPSCs) are the most diagnosed type of stem cells isolated from dental tissues. Previous studies demonstrate that tissues in earlier stages of development could be better stem cell resources for tissue engineering. AIMS: In this study, aiming at finding younger stem cell resources, we chose the pulp of human unerupted third molar teeth when the crown was completely formed and the roots had not begun their development, Nolla's 6 th developmental stage (N6 th ). MATERIALS AND METHODS: Surgical removal of the third molar was performed by aseptic technique with minimal trauma. The tissues were digested enzymatically and the resulted single cells were cultured. Immunophenotypic characterization of the cells was done via immunocytochemistry, immunofluorescence, and flow cytometry assays. Adipogenic and osteogenic differentiation potential of these cells was examined and confirmed by histochemical staining and reverse transcription-polymerase chain reaction analysis. STATISTICAL ANALYSIS USED: This study is descriptive. RESULTS: N6 th -unerupted dental pulp cultured cells expressed DPSC markers: Vimentin, CD73, CD90, CD105, CD166, CD44, CD146, and STRO-1, but did not express hematopoietic cell markers: CD14, CD34, CD45, HLA-DR and were also negative for dentin sialoprotein negative showing an undifferentiated preodontogenic state. Adipocytes differentiated from N6 th -DPSCs were positively stained with Oil-Red-O and expressed both early and late adipocyte specific genes. Formation of Alizarin-red positive condensed calcium-phosphate nodules accompanied by strong expression of two osteogenic mRNAs, exhibited osteogenic differentiation. CONCLUSION: Based on the results of this study, we suggest that N6 th -DMSCs are a viable choice for cryo-banking and future usage in regenerative therapies; however, more investigations are necessary before clinical application can commence.

Role of CD271 enrichment in the isolation of mesenchymal stromal cells from umbilical cord blood.

Isolation of mesenchymal stromal cells (MSCs) from the umbilical cord blood (UCB) has a success rate of 25% and is frequently contaminated by osteoclast-like cells (OLCs). CD271 is a well-known marker for the enrichment of bone marrow (BM) MSCs. We have assessed the effect of CD271 isolation on the isolation rate of MSCs from UCB. Twenty-one samples of UCB were collected. Ten samples of UCB and five of BM underwent CD271 isolation using magnetic activated cell sorting. The other 11 UCB samples were used as the control. The isolated cells were cultured and MSC isolation was confirmed with respect to morphology, flow cytometry, adipogenic and osteogenic differentiation potentials. CD271-positive UCB cells did not show outgrowth despite 54.5% MSCs isolation in the non-enriched portion. No OLC was noted in the CD271-enriched group, but 66% of the non-enriched samples were contaminated. All the CD271-positive BM cells formed MSC colonies. Although the per cent of CD271+ cells showed no difference between BM-mononuclear cells (MNCs) and UCB-MNCs, the haematopoietic marker, CD45, was found in a higher percentage of CD271-positive UCB-MNCs. The results of our study indicate that, although CD271 is a valuable marker for enrichment of MSCs from BM, it does not contribute to isolation of MSCs from UCB. In this source, most of the CD271+ cells are from haematopoietic origin, and possibly the process of isolation may eliminate the very low frequent MSCs and the isolation therefore fails.

Critical Role of Transforming Growth Factor Beta in Different Phases of Wound Healing.

SIGNIFICANCE: This review highlights the critical role of transforming growth factor beta (TGF-ß)1-3 within different phases of wound healing, in particular, late-stage wound healing. It is also very important to identify the TGF-ß1-controlling factors involved in slowing down the healing process upon wound epithelialization. RECENT ADVANCES: TGF-ß1, as a growth factor, is a known proponent of dermal fibrosis. Several strategies to modulate or regulate TGF's actions have been thoroughly investigated in an effort to create successful therapies. This study reviews current discourse regarding the many roles of TGF-ß1 in wound healing by modulating infiltrated immune cells and the extracellular matrix. CRITICAL ISSUES: It is well established that TGF-ß1 functions as a wound-healing promoting factor, and thereby if in excess it may lead to overhealing outcomes, such as hypertrophic scarring and keloid. Thus, the regulation of TGF-ß1 in the later stages of the healing process remains as critical issue of which to better understand. FUTURE DIRECTIONS: One hypothesis is that cell communication is the key to regulate later stages of wound healing. To elucidate the role of keratinocyte/fibroblast cross talk in controlling the later stages of wound healing we need to: (1) identify those keratinocyte-released factors which would function as wound-healing stop signals, (2) evaluate the functionality of these factors in controlling the outcome of the healing process, and (3) formulate topical vehicles for these antifibrogenic factors to improve or even prevent the development of hypertrophic scarring and keloids as a result of deep trauma, burn injuries, and any type of surgical incision.

Adipose tissue derived mesenchymal stem cell (AD-MSC) promotes skin wound healing in diabetic rats.

AIMS: Stem cells are a new hope to ameliorate impaired diabetic wound healing. The purpose of this study was to evaluate the effect of adipose tissue derived mesenchymal stem cells (AD-MSCs) on wound healing in a diabetic rat model. METHODS: Twenty-six rats became diabetic by a single intraperitoneal injection of streptozotocin. Six rats served as non-diabetic (non-DM). Diabetic rats were divided into two equal groups randomly; control and treatment. Six weeks later, a full-thickness circular excisional wound was created on the dorsum of each rat. AD-MSCs were injected intra-dermally around the wounds of treatment group. PBS was applied to control and non-DM groups. The wound area was measured every other day. After wound healing completion, full thickness skin samples were taken from the wound sites for evaluation of volume density of collagen fibers, length and volume density of vessels, and numerical density of fibroblasts by stereological methods. RESULTS: AD-MSCs accelerated wound healing rate in diabetic rats, but did not increase length and volume density of the vessels and volume density of the collagen fibers. AD-MSCs decreased the numerical density of fibroblasts. CONCLUSIONS: We concluded that AD-MSCs enhances diabetic wound healing rate probably by other mechanisms rather than enhancing angiogenesis or accumulating collagen fibers.

A comparison between different existing methods used to separate epidermal cells from skin biopsies for autologous transplantation.

BACKGROUND: Burn surgeons use autologous skin graft technique for patients, but a challenge remains for large surface wounds. Recently, a method was described which used a small piece of skin to cover a 70 times greater surface by spraying epidermal cells on injured skin. We designed a comparative study to find the best method to make an epidermal cell suspension. MATERIALS AND METHODS: Eleven discarded skin samples were sent to our laboratory from Ghotboddin Burn Hospital, Shiraz. Each sample was sliced into four small pieces (1 cm(2)) and each piece was treated with a different chemical including sodium bromide (2N) and (4N), ammonium hydroxide (2N), and trypsin (0.05%) for 20 minutes. The epidermis and dermis were separated using forceps. Trypsin was added to all samples (except the trypsinized sample) to begin the intercellular detachment. Afterward, epidermis was sliced into small pieces followed by filtration and centrifugation. Cells were counted using hemocytometer. Identification of keratinocytes and melanocytes was made through immunocytochemical staining for cytokeratin and melanosome antigens, respectively. RESULTS: There was a significant difference in alive cell counts comparing cells obtained from NaBr (4N) method to other methods. Considering total cell count and alive cell count, NaBr (4N) yielded the most cells. Immunocytochemical staining showed that in all methods, some cells are stained positively for cytokeratin antibody and some for melanosome antibody. CONCLUSION: Although recent papers had advised trypsin method to make a cell suspension to use for burn patients, we found that NaBr (4N) method yields more alive cells and less toxicity.