A multifunctional hydrogel loaded with two nanoagents improves the pathological microenvironment associated with radiation combined with skin wounds.

Persistent oxidative stress and recurring waves of inflammation with excessive reactive oxygen species (ROS) and free radical accumulation could be generated by radiation. Exposure to radiation in combination with physical injuries such as wound trauma would produce a more harmful set of medical complications, which was known as radiation combined with skin wounds (RCSWs). However, little attention has been given to RCSW research despite the unsatisfactory therapeutic outcomes. In this study, a dual-nanoagent-loaded multifunctional hydrogel was fabricated to ameliorate the pathological microenvironment associated with RCSWs. The injectable, adhesive, and self-healing hydrogel was prepared by crosslinking carbohydrazide-modified gelatin (Gel-CDH) and oxidized hyaluronic acid (OHA) through the Schiff-base reaction under mild condition. Polydopamine nanoparticles (PDA-NPs) and mesenchymal stem cell-secreted small extracellular vesicles (MSC-sEV) were loaded to relieve radiation-produced tissue inflammation and oxidation impairment and enhance cell vitality and angiogenesis individually or jointly. The proposed PDA-NPs@MSC-sEV hydrogel enhanced cell vitality, as shown by cell proliferation, migration, colony formation, and cell cycle and apoptosis assays in vitro, and promoted reepithelization by attenuating microenvironment pathology in vivo. Notably, a gene set enrichment analysis of proteomic data revealed significant enrichment with adipogenic and hypoxic pathways, which play prominent roles in wound repair. Specifically, target genes were predicted based on differential transcription factor expression. The results suggested that MSC-sEV- and PDA-NP-loaded multifunctional hydrogels may be promising nanotherapies for RCSWs. STATEMENT OF SIGNIFICANCE: The small extracellular vesicle (sEV) has distinct advantages compared with MSCs, and polydopamine nanoparticles (PDA-NPs), known as the biological materials with good cell affinity and histocompatibility which have been reported to scavenge ROS free radicals. In this study, an adhesive, injectable, self-healing, antibacterial, ROS scavenging and amelioration of the radiation related microenvironment hydrogel encapsulating nanoscale particles of MSC-sEV and PDA-NPs (PDA-NPs@MSC-sEV hydrogel) was synthesized for promoting radiation combined with skin wounds (RCSWs). GSEA analysis profiled by proteomics data revealed significant enrichments in the regulations of adipogenic and hypoxic pathways with this multi-functional hydrogel. This is the first report of combining this two promising nanoscale agents for the special skin wounds associated with radiation.

Single-Cell and Spatial Transcriptomics Decodes Wharton's Jelly-Derived Mesenchymal Stem Cells Heterogeneity and a Subpopulation with Wound Repair Signatures.

The highly heterogeneous characteristics of Wharton's jelly mesenchymal stem cells (WJ-MSCs) may be responsible for the poor clinical outcomes and poor reproducibility of treatments based on WJ-MSCs. Exploration of WJ-MSC heterogeneity with multimodal single-cell technologies will aid in establishing accurate MSC subtyping and developing screening protocols for dominant functional subpopulations. Here, the characteristics of WJ-MSCs are systematically analyzed by single cell and spatial transcriptome sequencing. Single-cell transcriptomics analysis identifies four WJ-MSC subpopulations, namely proliferative_MSCs, niche-supporting_MSCs, metabolism-related_MSCs and biofunctional-type_MSCs. Furthermore, the transcriptome, cellular heterogeneity, and cell-state trajectories of these subpopulations are characterized. Intriguingly, the biofunctional-type MSCs (marked by S100A9, CD29, and CD142) selected in this study exhibit promising wound repair properties in vitro and in vivo. Finally, by integrating omics data, it has been found that the S100A9+ CD29+ CD142+ subpopulation is more enriched in the fetal segment of the umbilical cord, suggesting that this subpopulation deriving from the fetal segment may have potential for developing into an ideal therapeutic agent for wound healing. Overall, the presented study comprehensively maps the heterogeneity of WJ-MSCs and provides an essential resource for future development of WJ-MSC-based drugs.

Wharton's jelly mesenchymal stem cell-derived small extracellular vesicles as natural nanoparticles to attenuate cartilage injury via microRNA regulation.

The main strategy of tissue repair and regeneration focuses on the application of mesenchymal stem cells and cell-based nanoparticles, but there are still multiple challenges that may have negative impacts on human safety and therapeutic efficacy. Cell-free nanotechnology can effectively overcome these obstacles and limitations. Mesenchymal stem cell (MSC)-derived natural small extracellular vesicles (sEVs) represent ideal nanotherapeutics due to their low immunogenicity and lack of tumorigenicity. Here, sEVs harvested from Wharton's jelly mesenchymal stem cells (WJMSCs) were identified. In vitro results showed that WJMSC-sEVs efficiently entered chondrocytes in the osteoarthritis (OA) model, further promoted chondrocyte migration and proliferation and modulated immune reactivity. In vivo, WJMSC-sEVs notably promoted chondrogenesis, which was consistent with the effect of WJMSCs. RNA sequencing results revealed that sEV-microRNA-regulated biocircuits can significantly contribute to the treatment of OA, such as by promoting the activation of the calcium signaling pathway, ECM-receptor interaction pathway and NOTCH signaling pathway. In particular, let-7e-5p, which is found in WJMSC-sEVs, was shown to be a potential core molecule for promoting cartilage regeneration by regulating the levels of STAT3 and IGF1R. Our findings suggest that WJMSC-sEV-induced chondrogenesis is a promising innovative and feasible cell-free nanotherapy for OA treatment.

Comparison of Curative Effect of Human Umbilical Cord-Derived Mesenchymal Stem Cells and Their Small Extracellular Vesicles in Treating Osteoarthritis.

INTRODUCTION: Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and their small extracellular vesicles (hUC-MSC-sEVs) have shown attractive prospects applying in regenerative medicine. This study aimed to compare the therapeutic effects of two agents on osteoarthritis (OA) and investigate underlying mechanism using proteomics. METHODS: In vitro, the proliferation and migration abilities of chondrocytes treated with hUC-MSCs or hUC-MSC-sEVs were detected by Cell Counting Kit-8 assay and scratch wound assay. In vivo, hUC-MSCs (a single dose of 5 × 105) or hUC-MSC-sEVs (30 µg/time) were injected into the knee joints of anterior cruciate ligament transection-induced OA model. Hematoxylin and eosin, Safranin O/Fast Green staining were used to observe cartilage degeneration. The levels of cartilage matrix metabolic molecules (Collagen II, MMP13 and ADAMTS5) and macrophage polarization markers (CD14, IL-1ß, IL-10 and CD206) were assessed by immunohistochemistry. Finally, proteomics analysis was performed to characterize the proteinaceous contents of two agents. RESULTS: In vitro data showed that hUC-MSC-sEVs were taken up by chondrocytes. A total of 15 µg/mL of sEVs show the greatest proliferative and migratory capacities among all groups. In the animal study, hUC-MSCs and hUC-MSC-sEVs alleviated cartilage damage. This effect was mediated via maintaining cartilage homeostasis, as was confirmed by upregulation of the COL II and downregulation of the MMP13 and ADAMTS5. Moreover, the M1 macrophage markers (CD14) were significantly reduced, while the M2 macrophage markers (CD206 and IL-10) were increased in the hUC-MSCs and hUC-MSC-sEVs relative to the untreated group. Mechanistically, we found that many proteins connected to cartilage repair were more abundant in sEVs. Notably, compared to hUC-MSCs, the upregulated proteins in sEVs were mostly involved in the regulation of immune effector process, extracellular matrix organization, PI3K-AKT signaling pathways, and Rap1 signaling pathway. CONCLUSION: Our study indicated that hUC-MSC-sEVs protect cartilage from damage and many cartilage repair-related proteins are probably involved in the restoration process. These data suggest the promising potential of hUC-MSC-sEVs as a therapeutic agent for OA.

Comparison of the Efficacy and Safety of Cell-Assisted Lipotransfer and Platelet-Rich Plasma Assisted Lipotransfer: What Should We Expect from a Systematic Review with Meta-Analysis?

Due to the high absorption rate of traditional autologous fat grafting, cell-assisted lipotransfer (CAL) and platelet-rich plasma (PRP)-assisted lipotransfer were developed. The purpose of this article was to evaluate the efficacy and safety of CAL and PRP in promoting the survival of autologous fat grafting through systematic review and meta-analysis. We searched Pubmed, Cochrane Library, Web of Science, and EMBASE for clinical studies on CAL and PRP-assisted lipotransfer published from January 2010 to January 2020. Then a meta-analysis was performed to assess the efficacy of CAL and PRP-assisted lipotransfer through data analysis of fat survival rate. We also assessed the incidence of complications and multiple operations to analyze their safety. A total of 36 studies (1697 patients) were included in this review. Regardless of the recipient area, CAL and PRP-assisted lipotransfer significantly improved the fat survival rate (CAL vs non-CAL: 71% vs 48%, P < 0.0001; PRP vs non-PRP: 70% vs 40%, P < 0.0001; CAL vs PRP: 71% vs 70%, P = 0.7175). However, in large-volume fat grafting, such as breast reconstruction, both increased the incidence of complications and did not decrease the frequency of multiple operations after lipotransfer. Further prospective studies are needed to evaluate the clinical benefits of CAL and PRP-assisted lipotransfer.

Will mesenchymal stem cells be future directions for treating radiation-induced skin injury?

Radiation-induced skin injury (RISI) is one of the common serious side effects of radiotherapy (RT) for patients with malignant tumors. Mesenchymal stem cells (MSCs) are applied to RISI repair in some clinical cases series except some traditional options. Though direct replacement of damaged cells may be achieved through differentiation capacity of MSCs, more recent data indicate that various cytokines and chemokines secreted by MSCs are involved in synergetic therapy of RISI by anti-inflammatory, immunomodulation, antioxidant, revascularization, and anti-apoptotic activity. In this paper, we not only discussed different sources of MSCs on the treatment of RISI both in preclinical studies and clinical trials, but also summarized the applications and mechanisms of MSCs in other related regenerative fields.

Combination of lyophilized adipose-derived stem cell concentrated conditioned medium and polysaccharide hydrogel in the inhibition of hypertrophic scarring.

BACKGROUND: Mesenchymal stem cell-based acellular therapies have been widely exploited in managing hypertrophic scars. However, low maintenance dose and transitory therapeutic effects during topical medication remain a thorny issue. Herein, this study aimed to optimize the curative effect of adipose-derived stem cell conditioned medium (ADSC-CM) in the prevention of hypertrophic scarring. METHODS: In the present study, ADSC-CM was concentrated via the freeze-drying procedure. The efficacy of different dose groups (CM, CM5, CM10) was conducted on the proliferation, apoptosis, and α-smooth muscle actin (α-SMA) expression of human keloid fibroblasts (HKFs) in vitro. Incorporation of adipose-derived stem cell concentrated conditioned medium (ADSCC-CM) into polysaccharide hydrogel was investigated in rabbit ear, in vivo. Haematoxylin-eosin (H&E) and Masson's trichrome staining were performed for the evaluation of scar hyperplasia. RESULTS: We noted that ADSCC-CM could downregulate the α-SMA expression of HKFs in a dose-dependent manner. In the rabbit ear model, the scar hyperplasia in the medium-dose group (CM5) and high-dose group (CM10) was inhibited with reduced scar elevation index (SEI) under 4 months of observation. It is noteworthy that the union of CM5 and polysaccharide hydrogel (CM5+H) yielded the best preventive effect on scar hyperplasia. Briefly, melanin, height, vascularity, and pliability in the CM5+H group were better than those of the control group. Collagen was evenly distributed, and skin appendages could be regenerated. CONCLUSIONS: Altogether, ADSCC-CM can downregulate the expression of α-SMA due to its anti-fibrosis effect and promote the rearrangement of collagen fibres, which is integral to scar precaution. The in situ cross bonding of ADSCC-CM and polysaccharide hydrogel could remarkably enhance the therapeutic outcomes in inhibiting scar proliferation. Hence, the alliance of ADSCC-CM and hydrogel may become a potential alternative in hypertrophic scar prophylaxis.

Does Cervical Sagittal Balance Affect the Preoperative Neck Disability Index in Patients With Cervical Myelopathy?

STUDY DESIGN: This was a retrospective study. OBJECTIVE: This study aimed to ascertain the relationship between preoperative Neck Disability Index (NDI) scores and cervical sagittal alignment in patients with cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: Cervical alignment may influence postoperative clinical outcomes. However, the effect of preoperative sagittal balance on the preoperative status in CSM patients remains uncertain. MATERIALS AND METHODS: From 2010 to 2016, 90 patients who underwent cervical surgery for CSM were enrolled. The inclusion criteria for this study included preoperative standing cervical radiographs and a preoperative NDI score. The following radiographic parameters were measured: (1) C0-C2 lordosis, (2) C2-C7 lordosis, (3) C2-C7 sagittal vertical axis (SVA), (4) neck tilt, (5) thoracic inlet angle, (6) T1 slope, and (7) T1 slope minus cervical lordosis (T1S-CL). The Pearson product-moment correlation coefficients were calculated between all radiographic variables and the NDI scores, and multiple regression analysis was performed to determine the independent predictors of high preoperative NDI scores. RESULTS: Both C2-C7 SVA and T1S-CL were positively correlated with NDI scores (r=0.732, P<0.001 and r=0.333, P=0.001). Cervical lordosis was negatively correlated with NDI scores (r=-0.267, P=0.011). Significant correlations were found between C2-C7 SVA and the C0-C2 Cobb angle (r=0.244, P=0.020), C2-C7 SVA and the C2-C7 Cobb angle (r=-0.359, P=0.001), the C2-C7 Cobb angle and the C0-C2 Cobb angle (r=-0.457, P<0.001), and the C2-C7 Cobb angle and T1 slope (r=-0.385, P<0.001). CONCLUSIONS: The disability of the neck increased with increasing C2-C7 SVA and T1S-CL and decreasing cervical lordosis before surgical reconstruction. High C2-C7 SVA, low thoracic inlet angle, and high neck tilt values are independent predictors of high preoperative NDI scores.