Human skin harbours multiple different stem cell populations. In contrast to the relatively well-characterized niches of epidermal and hair follicle stem cells, the localization and niches of stem cells in other human skin compartments are as yet insufficiently investigated. Previously, we had shown in a pilot study that human sweat gland stroma contains Nestin-positive stem cells. Isolated sweat gland stroma-derived stem cells (SGSCs) proliferated in vitro and expressed Nestin in 80% of the cells. In this study, we were able to determine the precise localization of Nestin-positive cells in both eccrine and apocrine sweat glands of human axillary skin. We established a reproducible isolation procedure and characterized the spontaneous, long-lasting multipotent differentiation capacity of SGSCs. Thereby, a pronounced ectodermal differentiation was observed. Moreover, the secretion of prominent cytokines demonstrated the immunological potential of SGSCs. The comparison to human adult epidermal stem cells (EpiSCs) and bone marrow stem cells (BMSCs) revealed differences in protein expression and differentiation capacity. Furthermore, we found a coexpression of the stem cell markers Nestin and Iα6 within SGSCs and human sweat gland stroma. In conclusion the initial results of the pilot study were confirmed, indicating that human sweat glands are a new source of unique stem cells with multilineage differentiation potential, high proliferation capacity and remarkable self renewal. With regard to the easy accessibility of skin tissue biopsies, an autologous application of SGSCs in clinical therapies appears promising.
Vascularization is a key process in tissue engineering and regeneration and represents one of the most important issues in the field of regenerative medicine. Thus, several strategies to improve vascularization are currently under clinical evaluation. In this study, stem cells derived from human sweat glands were isolated, characterized, seeded in collagen scaffolds, and engrafted in a mouse full skin defect model for dermal regeneration. Results showed that these cells exhibit high proliferation rates and express stem cell and differentiation markers. Moreover, cells responded to angiogenic environments by increasing their migration (P<0.001) and proliferation (P<0.05) capacity and forming capillary-like structures. After seeding in the scaffolds, cells distributed homogeneously, interacting directly with the scaffold, and released bioactive molecules involved in angiogenesis, immune response, and tissue remodeling. In vivo, scaffolds containing cells were used to induce dermal regeneration. Here we have found that the presence of the cells significantly improved vascularization (P<0.001). As autologous sweat gland-derived stem cells are easy to obtain, exhibit a good proliferation capacity, and improve vascularization during dermal regeneration, we suggest that the combined use of sweat gland-derived stem cells and scaffolds for dermal regeneration might improve dermal regeneration in future clinical settings.
Claudins (CLDNs) are transmembrane proteins localised in the cell membrane of epithelial cells composing a structural and functional component of the tight junction protein complexes. In canine tumors deregulations of the CLDN expression patterns were described immunohistochemically. Targeting of claudin proteins has further been evaluated to establish novel therapeutic approaches by directed claudin binding. Precondition for the development of claudin targeting approaches in canine cells is the possibility to characterise claudin expression specifically and the availability of claudin positive cell lines. Herein PCR/qPCR assays were established allowing a rapid qualitative and quantitative characterisation of CLDN-1, -3, -4 and -7 gene expression in canine cell lines and tissues. Further commercially available antibodies were used to verify CLDN gene expression on protein level by Western blots. The developed assays were used to analyse six canine cell lines derived from mammary and prostate tissue for their CLDN-1, -3, -4 and -7 expressions. The canine cell line DT08/40 (prostate transitional cell carcinoma) was used for the establishment of specific CLDNs -1, -3, -4 and -7PCR/qPCR. The designed assays were verified by amplicon cloning and sequencing. Gene expressions were verified on protein level by Western blot. Additionally further cell lines were analysed for their CLDN-1, -3, -4 and -7 expression on mRNA and protein level (mammary derived cell lines: MTH53A (non-neoplastic), ZMTH3 (adenoma), MTH52C (carcinoma); prostate derived cell lines: DT08/46 and CT1258 (both adenocarcinoma).The screened cell lines showed expression for the CLDNs as follows: DT08/46 and DT08/40: CLDN-1, -3, -4 and -7 positive; CT1258: CLDN-1, -3, -4 and -7 negative; ZMTH3 and MTH52C: CLDN-1 and -7 positive, CLDN-3 and -4 negative; MTH53A: CLDN-1, -3 and -4 negative, CLDN-7 positive. Western blot analyses reflect the detected CLDN-1, -3, -4 and -7 expressions in the analysed cell lines. The established CLDN-1, -3, -4 and -7 PCR/qPCR assays allow a qualitative and quantitative characterisation of canine CLDN gene expression. Characterisation of CLDN expression in six canine cell lines led to the identification of two canine prostate tissue derived CLDN expressing cell lines. These cell lines serve as candidates for further research on CLDN-based functional and therapeutic approaches.
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