Background information. DMD (Duchenne muscular dystrophy) is a devastating X-linked disorder characterized by progressive muscle degeneration and weakness. The use of cell therapy for the repair of defective muscle is being pursued as a possible treatment for DMD. Mesenchymal stem cells have the potential to differentiate and display a myogenic phenotype in vitro. Since liposuctioned human fat is available in large quantities, it may be an ideal source of stem cells for therapeutic applications. ASCs (adipose-derived stem cells) are able to restore dystrophin expression in the muscles of mdx (X-linked muscular dystrophy) mice. However, the outcome when these cells interact with human dystrophic muscle is still unknown.Results. We show here that ASCs participate in myotube formation when cultured together with differentiating human DMD myoblasts, resulting in the restoration of dystrophin expression. Similarly, dystrophin was induced when ASCs were co-cultivated with DMD myotubes. Experiments with GFP (green fluorescent protein)-positive ASCs and DAPI (4 ,6-diamidino-2-phenylindole)-stained DMD myoblasts indicated that ASCs participate in human myogenesis through cellular fusion.Conclusions. These results show that ASCs have the potential to interact with dystrophic muscle cells, restoring dystrophin expression of DMD cells in vitro. The possibility of using adipose tissue as a source of stem cell therapies for muscular diseases is extremely exciting.

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Several IAP (inhibitor of apoptosis) proteins regulate cell fate decisions, and the X-linked IAP (XIAP) does so in part by inhibiting caspases, proteases that execute the apoptotic pathway. A tissue-specific homologue of XIAP, known as ILP2 (IAP-like protein 2), has previously been implicated in the control of apoptosis in the testis by direct inhibition of caspase 9. In examining this protein we found that the putative caspase 9 interaction domain is a surprisingly weak inhibitor and is also conformationally unstable. Comparison with the equivalent domain in XIAP demonstrated that the instability is due to the lack of a linker segment N-terminal to the inhibitory BIR (baculovirus IAP repeat) domain. Fusion of a 9-residue linker from XIAP to the N-terminus of ILP2 restored tight caspase 9 inhibition, dramatically increased conformational stability and allowed crystallization of the ILP2 BIR domain in a form strikingly similar to the XIAP third BIR domain. We conclude that ILP2 is an unstable protein, and cannot inhibit caspase 9 in a physiological way on its own. We speculate that ILP2 requires assistance from unidentified cellular factors to be an effective inhibitor of apoptosis in vivo.

Background information. Duchenne muscular dystrophy is a disease characterized by progressive and irreversible muscle degeneration for which there is no therapy. HUCB (human umbilical cord blood) has been considered as an important source of haematopoietic and mesenchymal stem cells, each having been shown to differentiate into distinct cell types. However, it remains unclear if these cells are able to differentiate into muscle cells.Results. We have showed that stem cells from HUCB did not differentiate into myotubes or express dystrophin when cultured in muscle-conditioned medium or with human muscle cells. However, delivery of GFP (green fluorescent protein)-transduced mononucleated cells from HUCB, which comprises both haematopoietic and mesenchymal populations, into quadriceps muscle of mdx (mouse dystrophy X-chromosome linked) mice resulted in the expression of human myogenic markers. After recovery of these cells from mdx muscle and in vitro cultivation, they were able to fuse and form GFP-positive myotubes that expressed dystrophin. Conclusions.These results indicate that chemical factors and cell-to-cell contact provided by in vitro conditions were not enough to trigger the differentiation of stem cells into muscle cells. Nevertheless, we showed that the HUCB-derived stem cells were capable of acquiring a muscle phenotype after exposure to an in vivo muscle environment, which was required to activate the differentiation programme.

Progesterone has been associated with the development of gestational diabetes (GD) due to the enhancement of insulin resistance. As b-cell apoptosis participates in type 1 and type 2 diabetes pathophysiology, we proposed the hypothesis that progesterone might contribute to the development of GD through a mechanism that also involves b-cell death. To address this question, RINm5F insulin-producing cells were incubated with progesterone (25-100 mM), in the presence or absence of a-tocopherol (40 mM). After 24 or 48 h, membrane integrity and DNA fragmentation were analyzed by flow cytometry. Caspase activity was used to identify the mode of cell death. The involvement of endoplasmic reticulum stress in the action of progesterone was investigated by western blotting. Oxidative stress was measured by 2',7'-dichlorofluorescein diacetate (DCFDA) oxidation. Isolated rat islets were used in similar experiments in order to confirm the effect of progesterone in primary b-cells. Incubation of RINm5F cells with progesterone increased the number of cells with loss of membrane integrity and DNA fragmentation. Progesterone induced generation of reactive species. Pre-incubation with a-tocopherol attenuated progesterone-induced apoptosis. Western blot analyses revealed increased expression of CREB2 and CHOP in progesteronetreated cells. Progesterone caused apoptotic death of rat islet cells and enhanced generation of reactive species. Our results show that progesterone can be toxic to pancreatic b-cells through an oxidative-stress-dependent mechanism that induces apoptosis. This effect may contribute to the development of GD during pregnancy, particularly under conditions that require administration of pharmacological doses of this hormone.

Epidermal differentiation is a complex process in which keratinocytes go through morphological and biochemical changes in approximately 15 to 30 days. Abnormal keratinocyte differentiation is involved in the pathophysiology of several skin diseases. In this scenario, mesenchymal stem cells (MSCs) emerge as a promising approach to study skin biology in both normal and pathological conditions. Herein, we have studied the differentiation of MSC from umbilical cord into keratinocytes. MSC were cultured in Dulbecco's modified Eagle's medium (DMEM) (proliferation medium) and, after characterization, differentiation was induced by culturing cells in a defined keratinocyte serum-free medium (KSFM) supplemented with epidermal growth factor (EGF) and calcium chloride ions.Cells cultivated in DMEM were used as control. Cultures were evaluated from day 1 to 23, based on the cell morphology, the expression of p63, involucrin and cytokeratins (KRTs) KRT5, KRT10 and KRT14, by quantitative polymerase chain reaction, Western blot analysis or immunofluorescence, and by the detection of epidermal kallikreins activity. In cells grown in keratinocyte serum-free medium with EGF and 1.8 mM calcium, KRT5 and KRT14 expression was shown at the first day, followed by the expression of p63 at the seventh day. KRT10 expression was detected from day seventh while involucrin was observed after this period.Data showed higher kallikrein (KLK) activity in KSFM-cultured cells from day 11th in comparison to control. These data indicate that MSC differentiated into keratinocytes similarly to that occurs in the human epidermis. KLK activity detection appears to be a good methodology for the monitoring the differentiation of MSC into the keratinocyte lineage, providing useful tools for the better understanding of the skin biology. K E Y W O R D S differentiation, epidermal markers, keratinocytes, mesenchymal stem cells, tissue kallikreins J Cell Biochem. 2019;120:13141-13155.wileyonlinelibrary.com/journal/jcb

Polymeric scaffolds incorporating plant-derived compounds, produced by electrospinning, have attracted attention in the field of skin tissue engineering. This study evaluates the sustained antioxidant activity of polycaprolactone (PCL)/gelatin nanofibers prepared by electrospinning and incorporating loaded liposomes of epigallocatechin-3-gallate (EGCG), a strong antibacterial and antioxidant molecule found in green tea, that significantly accelerates the wound-healing process. The morphology and the structural properties of the membranes were characterized by scanning electron microscopy (SEM) and FTIR spectroscopy. Results revealed that the EGCG released from PCL+gelatin nanofibers scavenges the toxic ROS species generated by exposure to either H 2 O 2 or UV radiation and slows down the oxidation events associated with damage. This study provides the basis for development of promising nanofiber formulations containing EGCG that might enhance repair/regeneration of skin tissue.

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