A combination of calcium phosphates with nanofibrous scaffolds holds promising potential for bone tissue engineering applications. In this study, nanohydroxyapatite (n-HA) was coated on the plasma-treated surface of electrospun poly(l-lactide) (PLLA) nanofibers and the capacity of fabricated scaffolds for bone formation was investigated in vitro using human cord blood derived unrestricted somatic stem cells (USSC) under osteogenic induction and in vivo after subcutaneous implantation. PLLA and n-HA-coated PLLA (n-HA/PLLA) scaffolds exhibited a nanofibrous structure with interconnected pores and suitable mechanical properties. These scaffolds were also shown to support attachment, spreading, and proliferation of USSC, as shown by their flattened normal morphology and MTT assay. During osteogenic differentiation, significantly higher values of ALP activity, biomineralization, and bone-related gene expression were observed on n-HA/PLLA compared to PLLA scaffolds. Subsequently, these markers were measured in higher amounts in USSC on PLLA nanofibers compared to TCPS. According to the in vivo results, ossification and formation of trabeculi was observed in the n-HA/PLLA scaffold compared to PLLA. Taking together, it was shown that nanofibrous structure enhanced osteogenic differentiation of USSC. Furthermore, surface-coated n-HA stimulated the effect of nanofibers on the orientation of USSC toward osteolineage. In addition, the n-HA/PLLA electrospun scaffold showed the capacity for ectopic bone formation in the absence of exogenous cells.

Exosomes derived from adipose tissue-derived mesenchymal stem cells (AD-MSCs) have immunomodulatory effects of T-cell inflammatory response and reduction of clinical symptoms on streptozotocin-induced of the type-1 diabetes mellitus (T1DM). Beside control group and untreated T1DM mice, a group of T1DM mice was treated with intraperitoneal injections of characterized exosomes derived from autologous AD-MSCs. Body weight and blood glucose levels were measured during the procedure. Histopathology and immunohistochemistry were used for evaluation of pancreatic islets using hemotoxylin and eosin (H&E) staining and anti-insulin antibody. Isolated splenic mononuclear cells (MNCs) were subjected to splenocytes proliferation assay using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, immunophenotyping of regulatory T cells and cytokines. A significant increase in the levels of interleukin-4 (IL-4), IL-10, and transforming growth factor-β, and a decrease in the levels of IL-17 and interferon-γ in concordance with the significant increase in the Treg cell ratio in splenic MNCs (P < 0.05) was shown in T1DM mice treated with AD-MSC's exosomes as compared to T1DM untreated mice. This amelioration of autoimmune reaction after treatment of T1DM mice with the AD-MSC exosomes was confirmed with a significant increase in islets using H&E staining and Immunohistochemistry analyses. As expected, body weight, blood glucose levels in a survival of T1DM mice treated with AD-MSC's exosomes were maintained stable in comparison to untreated T1DM mice. It can be concluded that AD-MSC's exosomes exert ameliorative effects on autoimmune T1DM through increasing regulatory T-cell population and their products without a change in the proliferation index of lymphocytes, which makes them more effective and practical candidates.