CD146+Mesenchymal stem cells treatment improves vascularization, muscle contraction and VEGF expression, and reduces apoptosis in rat ischemic hind limb

Intranasal delivery of small extracellular vesicles from specific subpopulation of mesenchymal stem cells mitigates traumatic spinal cord injury

Vascular injury following spinal cord injury (SCI) can significantly exacerbate secondary SCI and result in neurological dysfunction. Strategies targeting angiogenesis have demonstrated potential in enhancing functional recovery post-SCI. In the context of angiogenesis, the CD146+ and CD271+ subpopulations of mesenchymal stem cells (MSCs) have been recognized for their angiogenic capabilities in tissue repair. Small extracellular vesicles (sEVs) derived from MSCs are nanoscale vesicles containing rich bioactive components that play a crucial role in tissue regeneration. However, the precise role of sEVs derived from CD146+CD271+ UCMSCs (CD146+CD271+ UCMSC-sEVs) in SCI remain unclear. In this study, CD146+CD271+ UCMSC-sEVs were non-invasively administered via intranasal delivery, demonstrating a significant capacity to stimulate angiogenesis and improve functional recovery in mice following SCI. Furthermore, in vitro assessments revealed the effective enhancement of migration and tube formation capabilities of the murine brain microvascular endothelial cell line (bEnd.3) by CD146+CD271+UCMSC-sEVs. MicroRNA array analysis confirmed significant enrichment of multiple microRNAs within CD146+CD271+ UCMSC-sEVs. Subsequent in vivo and in vitro experiments demonstrated that CD146+CD271+ UCMSC-sEVs promote enhanced angiogenesis and improved functional recovery mediated by miR-27a-3p. Further mechanistic studies revealed that miR-27a-3p sourced from CD146+CD271+ UCMSC-sEVs enhances migration and tube formation of bEnd.3 cells in vitro by suppressing the expression of Delta Like Canonical Notch Ligand 4 (DLL4), thereby promoting angiogenesis in vivo. Collectively, our results demonstrate that a crucial role of CD146+CD271+ UCMSC-sEVs in inhibiting DLL4 through the transfer of miR-27a-3p, which leads to the promotion of angiogenesis and improved functional recovery after SCI.

A biomaterial-based therapy for lower limb ischemia using Sr/Si bioactive hydrogel that inhibits skeletal muscle necrosis and enhances angiogenesis

Muscle necrosis and angiogenesis are two major challenges in the treatment of lower-limb ischemic diseases. In this study, a triple-functional Sr/Si-containing bioceramic/alginate composite hydrogel with simultaneous bioactivity in enhancing angiogenesis, regulating inflammation, and inhibiting muscle necrosis was designed to treat lower-limb ischemic diseases. In particular, sodium alginate, calcium silicate and strontium carbonate were used to prepare injectable hydrogels, which was gelled within 10 min. More importantly, this composite hydrogel sustainedly releases bioactive Sr²⁺ and SiO₃ ^2- ions within 28 days. The biological activity of the bioactive ions released from the hydrogels was verified on HUVECs, SMCs, C2C12 and Raw 264.7 cells in vitro, and the therapeutic effect of the hydrogel was confirmed using C57BL/6 mouse model of femoral artery ligation in vivo. The results showed that the composite hydrogel stimulated angiogenesis, developed new collateral capillaries, and re-established the blood supply. In addition, the bioactive hydrogel directly promoted the expression of muscle-regulating factors (MyoG and MyoD) to protect skeletal muscle from necrosis, inhibited M1 polarization, and promoted M2 polarization of macrophages to reduce inflammation, thereby protecting skeletal muscle cells and indirectly promoting vascularization. Our results indicate that these bioceramic/alginate composite bioactive hydrogels are effective biomaterials for treating hindlimb ischemia and suggest that biomaterial-based approaches may have remarkable potential in treating ischemic diseases.

Secretome of Hypoxia-Preconditioned Mesenchymal Stem Cells Enhance Angiogenesis in Diabetic Rats with Peripheral Artery Disease

Background

Lower limb peripheral artery disease (PAD) is the main risk of diabetes mellitus which result to high mortality rate. Approximately, 50% of patients who receive several treatments have passed away or lost limbs at a year's follow-up. Secretome of hypoxia mesenchymal stem cells (S-MSCs) contains several active soluble molecules from hypoxia MSCs (H-MSCs) that capable inducing anti-inflammatory and vascular regeneration in PAD.

Objective

In this study, we investigated the therapeutic potential of S-MSCs in improving dynamic function and angiogenesis of PAD diabetic rats.

Methods

The PAD was established by the incision from the groin to the inner thigh and distal ligation of femoral arteries in rats with diabetes. Rats were administered with 200 µL and 400 µL S-MSCs that successfully filtrated using tangential flow filtration (TFF) system based on various molecular weight cut-off categories intravenously. ELISA assay was used to analyze the cytokines and growth factors contained in S-MSCs. Tarlov score were examined at day 1, 3, 5, 7, 10 and 14. The rats were sacrificed at day 14 and muscle tissues were collected for immunohistochemistry (IHC) and gene expression analysis.

Results

ELISA assay showed that S-MSCs provides abundant level of VEGF, PDGF, bFGF, IL-10 and TGFβ. In vivo administration of S-MSCs remarkably enhanced the Tarlov score. S-MSCs improved angiogenesis through enhancing VEGF gene expression and significantly increasing CD31 positive area in muscle tissue of PAD diabetic rats.

Conclusion

Our findings suggest that S-MSCs could improves dynamic function and angiogenesis in PAD diabetic rats.

miR-221/222 Promote Endothelial Differentiation of Adipose-Derived Stem Cells by Regulation of PTEN/PI3K/AKT/mTOR Pathway

Adipose-derived stem cells (ADSCs) are a type of adult mesenchymal stem cell that show a repair effect on ischemic tissues owing to their capacity for endothelial differentiation. MicroRNA-221/222 (miR-221/222) has been extensively studied in endothelial cells (ECs). However, the mechanism that regulates ADSCs differentiation into ECs remains unknown. In this study, we investigated the effects of miR-221/222-overexpression/silence in ADSCs on endothelial differentiation by constructing lentiviral vectors. Differentiation capacity was assessed by measuring the expression of endothelial markers (CD31, CD34, and CD144). In addition, low-density lipoprotein (LDL) uptake and tube-like formation were performed for evaluation of functional characterization. The PTEN/PI3K/AKT/mTOR signaling pathway was investigated using western blotting to clarify the action mechanism of this gene. The revascularization of miR-221/222-transfeted ADSCs was further verified in a rat hind limb ischemia model. The results confirmed that transfection with miR-221/222 promoted the expression of endothelial markers, LDL uptake, and tube-like formation. As expected, the PI3K/AKT signaling pathway was effectively activated when ADSCs showed high expression of miR-221/222 during endothelial differentiation. Furthermore, injection of miR-221/222 transfected ADSCs significantly improved rat hindlimb ischemia, as evidenced by increased blood flow and structural integrity and reduce inflammatory infiltration. The results of this study suggest that miR-221/222 is essential for endothelial differentiation of ADSCs and provides a novel strategy for modulating vascular formation and ischemic tissue regeneration.

Effects of Lycopene Attenuating Injuries in Ischemia and Reperfusion

Tissue and organ ischemia can lead to cell trauma, tissue necrosis, irreversible damage, and death. While intended to reverse ischemia, reperfusion can further aggravate an ischemic injury (ischemia-reperfusion injury, I/R injury) through a range of pathologic processes. An I/R injury to one organ can also harm other organs, leading to systemic multiorgan failure. A type of carotenoid, lycopene, has been shown to treat and prevent many diseases (e.g., rheumatoid arthritis, cancer, diabetes, osteoporosis, male infertility, neurodegenerative diseases, and cardiovascular disease), making it a hot research topic in health care. Some recent researches have suggested that lycopene can evidently ameliorate ischemic and I/R injuries to many organs, but few clinical studies are available. Therefore, it is essential to review the effects of lycopene on ischemic and I/R injuries to different organs, which may help further research into its potential clinical applications.

Optimization of a Pericyte Therapy to Improve Muscle Recovery After Limb Immobilization

Extended bed rest or limb immobilization can significantly reduce skeletal muscle mass and function. Recovery may be incomplete, particularly in older adults. Our laboratory recently reported that vascular mural cell (pericyte) quantity is compromised after immobilization and appropriate replacement immediately prior to remobilization can effectively recover myofiber size in mice. Identification of a single cell surface marker for isolation of the most therapeutic pericyte would streamline efforts to optimize muscle recovery. The purpose of this study was to compare the capacity for neural/glial antigen 2 (Cspg4/NG2⁺) and melanoma cell adhesion molecule (Mcam/CD146⁺) positive pericytes to uniquely recover skeletal muscle post-disuse. A single hindlimb from adult C57BL/6J mice was immobilized in full dorsiflexion via a surgical staple inserted through the center of the foot and body of the gastrocnemius. Fourteen days after immobilization, the staple was removed and pericytes, either NG2⁺CD45^-CD31^-[Lin^-], CD146⁺NG2^-Lin^-, or CD146⁺Lin^- pericytes, were injected into the atrophied tibialis anterior muscle. TA muscles were excised 14 days after transplantation and remobilization. Pericyte transplantation did not significantly improve muscle mass or myofiber CSA after 14 days of remobilization. However, injection of CD146⁺ pericytes significantly increased Type IIa quantity, capillarization and collagen remodeling compared to NG2⁺ pericytes (p<0.05). Our results suggest that selection of pericytes based on CD146 rather than NG2 results in the isolation of therapeutic mural cells with high capacity to positively remodel skeletal muscle after a period of immobilization.