Expression analysis of genes involved in the expansion of hematopoietic stem cells (SCF, Flt3-L, TPO, IL-3, and IL-6) in unrestricted somatic stem cells cultured on fibrin.

Umbilical cord blood (UCB) transplantation is a promising therapeutic approach for patients lacking HLA-matched donors. A main limitation to the use of UCB-derived HSCs (UCB-HSCs) is the low number of transplantable cells. Novel culture strategies are being developed to increase the number of HSCs. Unrestricted somatic stem cells (USSCs) have been identified as promising stromal cells for supporting HSC expansion. The current study aimed to explore the effect of fibrin on the expression of hematopoiesis-related genes (SCF, Flt3-L, TPO, IL-3, and IL-6) in USSCs. USSCs were isolated from UCB and characterized by flow cytometry and in vitro multilineage differentiation ability. DAPI staining and the MTT assay were used to assess the effect of fibrin on USSC viability. The cell attachment was evaluated using SEM. qRT-PCR was performed to evaluate the expression of SCF, Flt3-L, TPO, IL-3, and IL-6 in USSCs cultured on 3D fibrin scaffolds. USSCs were positive for CD73, CD105, and CD166 and negative for CD45. Alizarin red and Oil red O stains confirmed calcium deposition and lipid vacuoles in USSCs. Results obtained from DAPI and MTT assays revealed a positive effect of fibrin on USSC viability. Cells cultured on fibrin express significantly higher levels of SCF and TPO compared to those grown in a 2D environment. The positive effect of fibrin on IL-6 levels was reversed. Fibrin did not affect Flt3-L expression and IL-3 mRNA expression was not detected in either group. The results of this study provide the basis for developing further research on the ex vivo expansion of HSCs with USSCs.

Exosomes derived from mesenchymal stem cells: A promising cell-free therapeutic tool for cutaneous wound healing.

Skin wound healing is a multifaceted process involving a cascade of molecular and cellular procedures that occur in four different phases: (a) hemostasis, (b) inflammation, (c) proliferation, and (d) tissue remodeling. Prolonged wound healing in skin is still a major challenge in treatment of wounds. Mesenchymal stem cells (MSCs) accelerate cutaneous wound healing through their paracrine activity. Exosomes are one of the key secretory products of MSCs, mimicking the effects of parental MSCs in skin wound healing process. Exosomes are small membrane vesicles (30-150 nm in diameter) that originate from endosomal pathways and transport numerous biomolecules, including DNAs, messenger RNAs, microRNAs, lipids, and proteins. They can be taken up by target cells and release their contents to modulate the activity of recipient cells. Exosomes derived from mesenchymal stem cells (MSC-Exo) reduce inflammation, promote proliferation, inhibit apoptosis, and enhance angiogenesis in skin wound healing process. Therefore, exosomes are emerging as novel cell-cell communication mediators and have opened a novel viewpoint for developing cell-free therapies. This review aims to demonstrate the roles of exosomes in each step of skin wound healing through a comprehensive literature search.