P-MSC-derived extracellular vesicles facilitate diabetic wound healing via miR-145-5p/ CDKN1A-mediated functional improvements of high glucose-induced senescent fibroblasts.

Background: Persistent hyperglycaemia in diabetes causes functional abnormalities of human dermal fibroblasts (HDFs), partially leading to delayed skin wound healing. Extracellular vesicles (EVs) containing multiple pro-healing microRNAs (miRNAs) have been shown to exert therapeutic effects on diabetic wound healing. The present study aimed to observe the effects of EVs derived from placental mesenchymal stem cells (P-MSC-EVs) on diabetic wound healing and high glucose (HG)-induced senescent fibroblasts and to explore the underlying mechanisms. Methods: P-MSC-EVs were isolated by differential ultracentrifugation and locally injected into the full-thickness skin wounds of diabetic mice, to observe the beneficial effects on wound healing in vivo by measuring wound closure rates and histological analysis. Next, a series of assays were conducted to evaluate the effects of low (2.28 x 1010 particles/ml) and high (4.56 x 1010 particles/ml) concentrations of P-MSC-EVs on the senescence, proliferation, migration, and apoptosis of HG-induced senescent HDFs in vitro. Then, miRNA microarrays and real-time quantitative PCR (RT-qPCR) were carried out to detect the differentially expressed miRNAs in HDFs after EVs treatment. Specific RNA inhibitors, miRNA mimics, and small interfering RNA (siRNA) were used to evaluate the role of a candidate miRNA and its target genes in P-MSC-EV-induced improvements in the function of HG-induced senescent HDFs. Results: Local injection of P-MSC-EVs into diabetic wounds accelerated wound closure and reduced scar widths, with better-organized collagen deposition and decreased p16INK4a expression. In vitro, P-MSC-EVs enhanced the antisenescence, proliferation, migration, and antiapoptotic abilities of HG-induced senescent fibroblasts in a dose-dependent manner. MiR-145-5p was found to be highly enriched in P-MSC-EVs. MiR-145-5p inhibitors effectively attenuated the P-MSC-EV-induced functional improvements of senescent fibroblasts. MiR-145-5p mimics simulated the effects of P-MSC-EVs on functional improvements of fibroblasts by suppressing the expression of cyclin-dependent kinase inhibitor 1A and activating the extracellular signal regulated kinase (Erk)/protein kinase B (Akt) signaling pathway. Furthermore, local application of miR-145-5p agomir mimicked the effects of P-MSC-EVs on wound healing. Conclusions: These results suggest that P-MSC-EVs accelerate diabetic wound healing by improving the function of senescent fibroblasts through the transfer of miR-145-5p, which targets cyclin-dependent kinase inhibitor 1A to activate the Erk/Akt signaling pathway. P-MSC-EVs are promising therapeutic candidates for diabetic wound treatment.

Photobiomodulation Therapy With Different Wavebands for Hair Loss: A Systematic Review and Meta-Analysis.

BACKGROUND: Photobiomodulation is a promising therapy for hair loss with negligible side effects. However, the reported effects of photobiomodulation therapy for hair loss are inconsistent. OBJECTIVE: To assess the curative effect of photobiomodulation therapy for the treatment of hair loss. METHODS: A systematic review of self-controlled studies and randomized controlled trials was conducted. ScienceDirect, PubMed, and Wiley Online Library were searched from the earliest date to May 30, 2021. RESULTS: Thirty-six studies (966 patients) were included. Two to 4 meta-analyses with different indices were performed separately on 4 groups of studies to test the effectiveness of the following hair loss treatments: ultraviolet light for alopecia areata (AA), red light for androgenetic alopecia (AGA), infrared light for AA, and infrared light for AGA. All meta-analyses showed that treatments were superior to control ( p < .05). CONCLUSION: The meta-analyses strongly suggested that photobiomodulation therapies with ultraviolet and infrared light were effective for treating AA, and photobiomodulation therapies with red light and infrared light were effective for treating AGA.

Photobiomodulation promotes hair regeneration in injured skin by enhancing migration and exosome secretion of dermal papilla cells.

The application of photobiomodulation (PBM) in regenerative medicine has expanded to the treatment of alopecia caused by various reasons. However, the mechanisms responsible for its effects are poorly understood. Here, we aimed to investigate the effects of PBM on hair regeneration in injured skin and to explore the underlying mechanisms. The scratched epidermis or dermis models were established in C57 mice aged 7-8 weeks. We found that the scratched epidermis had no influence on hair regeneration, but the scratched dermis led to obvious hair follicle atrophy and significantly influenced hair regeneration. The wounds in scratched dermis models were treated with PBM (655 nm, 3 J/cm2 [10 min]) and the hair regeneration and cell proliferation in hair follicle were evaluated. Compared with control, the hair coverage level was significantly enhanced after PBM treatment. Sox9+ and PCNA+ cells in hair follicle were obviously observed in PBM-treated group, but not in control. In vitro, the effects of PBM on the function of dermal papilla cells (DPCs) were investigated. The results showed that the migration of DPCs was increased significantly by PBM (655 nm, 3 J/cm2 [10 min]), whereas no effect was found on proliferation. Furthermore, we found that PBM promoted exosome secretion of DPCs, accompanied by the activation of Akt/GSK-3ß/ß-catenin pathway. AKT inhibitor MK-2206 effectively blocked PBM-induced migration and exosome secretion of DPCs. These findings suggest that the enhanced migration and exosome secretion of DPCs mediated by the Akt/GSK-3ß/ß-catenin pathway were responsible for the promotion of hair regeneration in injured skin by PBM.

Manipulation of living cells with 450 nm laser photobiomodulation.

Increasing studies demonstrated that photobiomodulation (PBM) influenced specific biological effects in cells, tissues and organs, and these effects rely on the production of light irradiation. In this study, we aimed to precisely manipulate the spatial arrangement of adhesion cells in a traditional culture condition with 450 nm low intensity laser. Through 450 nm laser PBM, the adhesion of the cultured cells was significantly improved and resisted the digestion of 0.1% trypsin. Combined with a computer aided design system (CAD) and computer numerical control (CNC) system, the designed laser irradiation pattern induced the specific cell micropattern in the culture dish. RNA sequencing and biochemical experiments confirmed that the 450 nm laser prompted low-density lipoprotein (LDL) bonding to the cell surface and induced lipid peroxidation, which crosslinked and modified the protein molecules on the irradiated cell surface. In this way, the peroxidation product-modified proteins resisted trypsin proteolysis, ultimately leading to a differential detachment between the irradiated and non-irradiated cells under trypsin treatment. This convenient method did not require special biomaterial processing, has no impact on cell viability and functions, and required no changes to the conventional cell culture conditions. The photo-induced cell capturing is a great complement to existing tools by providing spatial resolution.

Reprogramming of Keratinocytes as Donor or Target Cells Holds Great Promise for Cell Therapy and Regenerative Medicine.

One of the most crucial branches of regenerative medicine is cell therapy, in which cellular material is injected into the patient to initiate the regenerative process. Cells obtained by reprogramming of the patient's own cells offer ethical and clinical advantages could provide a new source of material for therapeutic applications. Studies to date have shown that only a subset of differentiated cell types can be reprogrammed. Among these, keratinocytes, which are the most abundant proliferating cell type in the epidermis, have gained increasing attention as both donor and target cells for reprogramming and have become a new focus of regenerative medicine. As target cells for the treatment of skin defects, keratinocytes can be differentiated or reprogrammed from embryonic stem cells, induced pluripotent stem cells, fibroblasts, adipose tissue stem cells, and mesenchymal cells. As donor cells, keratinocytes can be reprogrammed or direct reprogrammed into a number of cell types, including induced pluripotent stem cells, neural cells, and Schwann cells. In this review, we discuss recent advances in keratinocyte reprogramming, focusing on the induction methods, potential molecular mechanisms, conversion efficiency, and safety for clinical applications. Graphical Abstract KCs as target cells can be reprogrammed or differentiated from fibroblasts, iPSCs, ATSCs, and mesenchymal cells. And as donor cells, KCs can be reprogrammed or directly reprogrammded into iPSCs, neural cells, Schwann cells, and epidermal stem cells.

Ultrasonography Superior Over Visual Assessment in Evaluation of Wound Healing After Dermabrasion.

BACKGROUND: Dermabrasion as one kind of treatment for partial thickness wounds is controversial. Visual assessment as the main way to evaluate the healing process of burn wounds is also inaccurate. In this study we try to explore whether dermabrasion accelerates healing in wounds of partial thickness and determine a reliable way to evaluate epithelialization. MATERIALS AND METHODS: Eight female Bama minipigs were anesthetized, and eighteen partial thickness wounds (circle, 4.0 cm2, symmetrically located at both sides of the spine) were produced on each. Wounds on the left side underwent dermabrasion (group D), and wounds on the right side did not (group N). All wounds were covered with allogenic skin (premade). The healing processes of the wounds were observed through three different ways, which included visual assessment, ultrasonography, and histological observation. The epithelialization rate (ER) for each day was plotted together to form a healing curve, by which theoretical mean healing times could be determined ("healed" was classified as ER = 95%). RESULTS: Through visual assessment, the healing times of group D and group N were 13.6 and 18.0 d, respectively. Using ultrasonography, wounds of group D and group N healed at 5.0 and 10.4 d, respectively. Through histological observation, full epithelialization was seen at 5.0 d in group D and at 10.2 d in group N. The healing curves based on visual assessment deviated far from those based on ultrasonography and histological observations, the two of which were almost duplicated. CONCLUSIONS: Earlier epithelialization could be seen in wounds of partial thickness burns after dermabrasion. It would be more accurate and reliable to monitor the epithelialization process through ultrasonography than visual assessment.

The role of TrkA in the promoting wounding-healing effect of CD271 on epidermal stem cells.

CD271, a receptor of nerve growth factor (NGF), affects the biological properties of epidermal stem cells (eSCs) which are essential for skin wound closure. Tropomyosin-receptor kinase A (TrkA), another receptor of NGF, combined with CD271 has been involved with nervous system and skin keratinocytes. However, the exact role of TrkA combined with CD271 in eSCs during skin wound closure is still unclear. This study aimed to reveal the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs. We obtained CD271-vo (over-expression of CD271) eSCs by lentiviral infection. K252a was used to inhibit TrkA expression. Full-thickness skin mouse wound closure model (5 mm in diameter) was used to detect the ability of CD271 over-expressed/TrkA-deficient during wound healing. The biological characteristics of eSCs and their proliferation and apoptosis were detected using immunohistochemistry and western blot. The expressions of protein kinase B (pAkt)/Akt, phosphorylated extracellular-signal-related kinase (pERK)/ERK1/2, and c-Jun N-terminal kinase (pJNK)/JNK were also detected by western blot. We found that over-expression of CD271 promoted the biological functions of eSCs. Interestingly, over-expression of CD271 in the absence of TrkA neither promoted eSCs' migration and proliferation nor promoted wound healing in a mouse model. In addition, we observed the reduced expression of pAkt/Akt and pERK/ERK1/2 following TrkA inhibition in vitro. Our studies demonstrated that the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs.

Nationwide web survey of pediatric scalds: Prevalence and the relationship with household vacuum flasks.

OBJECTIVE: To explore the prevalence of pediatric (0-72 months old) scalds, and to clarify its relationship with household vacuum flasks. METHODS: A cross sectional online survey based on the largest social media in China. Online questionnaire was pushed twice a day to our target respondents for successive seven days. We were authorized to gain, analyze and publish the information related to this research by the Sina & Weibo data center. RESULTS: Prevalence of pediatric scalds was 5.5%. Gender ratio (boy to girl) was 1.96:1. Toddlers (12-36 months old) were the most susceptible age group (54.5%). Non-intentional water spill was the main causation (77.3%). An extremely low percent (7.1%) of the parents performed first-aid as described by the "RRICH" rule: water rinse - clothes remove - water immersion - clean cover - hospital. Scars developed in 52.7% patients and 14.7% of them underwent reconstructive surgery. There were 75.5% Chinese families using vacuum flasks in daily life, but only 6.1% families used the fastening device to avoid burns. CONCLUSION: Prevalence of pediatric scalds (0-72 months old) was rather high, which might be related to the extensive insecure usage of household vacuum flasks.