Hypoxia-preconditioned adipose-derived stem cells combined with scaffold promote urethral reconstruction by upregulation of angiogenesis and glycolysis

Adipose stem cell-derived exosomes in the treatment of wound healing in preclinical animal models: a meta-analysis

Background

Wound healing has always been a serious issue for doctors and primary health care systems. In addition, adipose stem cell-derived exosomes have been proven to play a positive and effective role in tissue repair and regeneration. A systematic review of these preclinical studies was performed to assess the efficacy of adipose stem cell-derived exosomes (ADSC-Exos) in treating wounds. This article aimed to study the effectiveness of ADSC-Exos for the treatment of animal skin wounds and includes a meta-analysis of exosomes from general wounds and diabetic ulcer wounds in in vitro models of animals to provide a theoretical basis for clinical translation.

Methods

A total of 19 studies with 356 animals were identified by searching the PubMed, Cochrane, MEDLINE Complete, Web of Science, CNKI and Wanfang databases from inception to 15 November 2022. No language or time restrictions were applied. Stata17 was used for all the data analyses.

Results

The meta-analysis showed that ADSC-Exo therapy significantly improved the wound healing rate in the control group, except in the diabetes group on day 7. Day 7 of general wounds [standard mean difference (SMD) 2.87, 95% confidence interval (CI) 1.91-3.83)] and day 14 (SMD 2.89, 95%CI 1.47-4.30). Day 14 (SMD 3.43, 95%CI 1.28-5.58) of diabetic wounds. Other outcomes, such as blood vessel density, collagen deposition and wound re-epithelization, improved with the administration of ADSC-Exos.

Conclusions

A meta-analysis showed that ADSC-Exo therapy applied to general and diabetic wounds can promote neovascularization, improve epithelization and collagen fiber deposition, promote healing, and reduce scar formation. ADSC-Exos have broad potential in preclinical research and clinical fields.

Multilayered hydrogel scaffold construct with native tissue matched elastic modulus: A regenerative microenvironment for urethral scar-free healing

The unsuitable deformation stimulus, harsh urine environment, and lack of a regenerative microenvironment (RME) prevent scaffold-based urethral repair and ultimately lead to irreversible urethral scarring. The researchers clarify the optimal elastic modulus of the urethral scaffolds for urethral repair and design a multilayered PVA hydrogel scaffold for urethral scar-free healing. The inner layer of the scaffold has self-healing properties, which ensures that the wound effectively resists harsh urine erosion, even when subjected to sutures. In addition, the scaffold's outer layer has an extracellular matrix-like structure that synergizes with adipose-derived stem cells to create a favorable RME. In vivo experiments confirm successful urethral scar-free healing using the PVA multilayered hydrogel scaffold. Further mechanistic study shows that the PVA multilayer hydrogel effectively resists the urine-induced inflammatory response and accelerates the transition of urethral wound healing to the proliferative phase by regulating macrophage polarization, thus providing favorable conditions for urethral scar-free healing. This study provides mechanical criteria for the fabrication of urethral tissue-engineered scaffolds, as well as important insights into their design.

Positive effects of hypoxic preconditioning of the extracellular matrix and stromal vascular fraction from adipose tissue

Background

Numerous approaches have been developed to decelerate the aging process of facial skin. Synthetic fillers and cell-enriched fat grafts are the main procedures employed to fill wrinkles.

Objective

The aim of this study was to evaluate the in vitro and in vivo safety and efficiency of a new process developed by SYMBIOKEN: the AmeaCell, which facilitates the extraction of the stromal vascular fraction (SVF) and the associated hypoxia pre-conditioned matrix to promote fat graft survival.

Methods

The AmeaCell device allows the extraction from adipose tissue of SVF and pre-conditioned MatriCS and promotes a hypoxic environment. Experiments were carried out on human cells and then in mice.

Results

Characterization of cells and MatriCS showed that after their extraction using the new process developed by SYMBIOKEN, the extracted cells expressed stem-cell markers. The presence of characteristic proteins and lipid fractions found in the adipose matrix were confirmed in MatriCS. Cobalt chloride treatment of the matrix using the AmeaCell device induced modifications in the matrix composition with a decrease in laminin and without collagen modification, both of which promote adhesion and differentiation of SVF or adipose-derived stromal cells. The combination of MatriCS and SVF (1 × 106 and 5 × 106, respectively) is safe and efficient to fill winkles induced by UVB irradiation. The cross-talk between MatriCS and SVF can act a durable filler compared to the filling performed using cells or matrix or fat alone, which need to be replaced frequently.

Conclusion

These results indicate that the combination of MatriCS and SVF is safe and effective as a biological filler for achieving skin rejuvenation and wrinkle filling.

A Modified Small Intestinal Submucosa Patch with Multifunction to Promote Scarless Repair and Reinvigoration of Urethra

To reconstruct and restore the functions of the male urethra is a challenging task for urologists. The acellular matrix graft currently used in the clinics is mono-functional and may cause a series of complications including stricture, fibrosis, and stone formation. As a result, such graft materials cannot meet the increasing demand for multifunctionality in the field of urethral tissue engineering. In this context, a multifunctional urethral patch is designed for the repair of urethral defects by mixing protocatechualdehyde (PCA) with small intestinal submucosa (SIS) under an alkalin condition to allow cross linking. As shown, the PCA/SIS patch possesses excellent biocompatibility, antioxidant activity, and anti-inflammatory property. More importantly, this patch can remarkably promote the adhesion, proliferation, and directional extension of rabbit bladder epithelial mucous cells (R-EMCs) as well as rabbit bladder smooth muscle cells (R-SMCs), and upregulate the expression of cytokeratin in the EMCs and contractile protein in the SMCs in vitro. In vivo experiments also confirm that the PCA/SIS patch can significantly enhance scarless repair of urethral defects in rabbits by facilitating smooth muscle regeneration, reducing excessive collagen deposition, and accelerating re-epithelialization and neovascularization. Taken together, the newly developed multifunctional PCA/SIS patch provides a promising candidate for urethral regeneration.

Cell-Based Therapy for Urethral Regeneration: A Narrative Review and Future Perspectives

Urethral stricture is a common urological disease that seriously affects quality of life. Urethroplasty with grafts is the primary treatment, but the autografts used in clinical practice have unavoidable disadvantages, which have contributed to the development of urethral tissue engineering. Using various types of seed cells in combination with biomaterials to construct a tissue-engineered urethra provides a new treatment method to repair long-segment urethral strictures. To date, various cell types have been explored and applied in the field of urethral regeneration. However, no optimal strategy for the source, selection, and application conditions of the cells is available. This review systematically summarizes the use of various cell types in urethral regeneration and their characteristics in recent years and discusses possible future directions of cell-based therapies.

Adipose-Derived Stem Cells Improve Angiogenesis and Lymphangiogenesis in a Hypoxic Dermal Regeneration Model In Vitro

Background and Objectives: Impaired wound healing represents an unsolved medical issue with a high impact on patients’ quality of life and global health care. Even though hypoxia is a significant limiting factor for wound healing, it reveals stimulating effects in gene and protein expression at cellular levels. In particular, hypoxically treated human adipose tissue-derived stem cells (ASCs) have previously been used to stimulate tissue regeneration. Therefore, we hypothesized that they could promote lymphangiogenesis or angiogenesis. Materials and Methods: Dermal regeneration matrices were seeded with human umbilical vein endothelial cells (HUVECs) or human dermal lymphatic endothelial cells (LECs) that were merged with ASCs. Cultures were maintained for 24 h and 7 days under normoxic or hypoxic conditions. Finally, gene and protein expression were measured regarding subtypes of VEGF, corresponding receptors, and intracellular signaling pathways, especially hypoxia-inducible factor-mediated pathways using multiplex-RT-qPCR and ELISA assays. Results: All cell types reacted to hypoxia with an alteration of gene expression. In particular, vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor B (VEGFB), vascular endothelial growth factor C (VEGFC), vascular endothelial growth factor receptor 1 (VEGFR1/FLT1), vascular endothelial growth factor receptor 2 (VEGFR2/KDR), vascular endothelial growth factor receptor 3 (VEGFR3/FLT4), and prospero homeobox 1 (PROX1) were overexpressed significantly depending on upregulation of hypoxia-inducible factor 1 alpha (HIF-1a). Moreover, co-cultures with ASCs showed a more intense change in gene and protein expression profiles and gained enhanced angiogenic and lymphangiogenic potential. In particular, long-term hypoxia led to continuous stimulation of HUVECs by ASCs. Conclusions: Our findings demonstrated the benefit of hypoxic conditioned ASCs in dermal regeneration concerning angiogenesis and lymphangiogenesis. Even a short hypoxic treatment of 24 h led to the stimulation of LECs and HUVECs in an ASC-co-culture. Long-term hypoxia showed a continuous influence on gene expressions. Therefore, this work emphasizes the supporting effects of hypoxia-conditioned-ASC-loaded collagen scaffolds on wound healing in dermal regeneration.

Small extracellular vesicles derived from human adipose-derived stem cells regulate energetic metabolism through the activation of YAP/TAZ pathway facilitating angiogenesis

Recent studies have found small extracellular vesicles (sEVs) that are secreted from human adipose tissue-derived stem cells (hADSCs-sEVs) and contribute to angiogenesis. Glycolysis, the primary energetic pathway of vascular endothelial cells, plays a key role in the process of angiogenesis. However, hADSCs-sEVs' effects on energy metabolism within endothelial cells remain unclear. In our study, we found that hADSCs-sEVs restored glycolytic metabolism suppressed by 3-(pyridinyl)-1-(4-pyridinyl)-2-propen-1-one(3PO), a unique glycolytic inhibitor increasing the extracellular acidification rate (ECAR), oxygen consumption rate (OCR), glycolytic gene expression as well as pyruvate, lactate, and ATP production in HUVEC cells. In contrast, hADSCs-sEVs decreased PDH-E1α expression and acetyl-CoA production. The above results indicate that hADSCs-sEVs promote HUVEC angiogenesis via enhancing glycolysis and suppressing mitochondrial oxidative phosphorylation. Furthermore, we found that the YAP/TAZ pathway may play a key role in the effects hADSCs-sEVs have on HUVECs, thus, providing a promising approach for pro-angiogenesis-related regeneration.

Fibrinogen/poly(l-lactide-co-caprolactone) copolymer scaffold: A potent adhesive material for urethral tissue regeneration in urethral injury treatment

Since a scarcity of sufficient grafting materials, several complications can arise after urothelial defect reconstruction surgery, including severe hypospadias. Accordingly, developing alternative therapies, such as urethral restoration via tissue engineering are needed. In the present study, we developed a potent adhesive and repairing material using fibrinogen-poly(l-lactide-co-caprolactone) copolymer (Fib-PLCL) nanofiber scaffold to achieve effective urethral tissue regeneration after seeding with epithelial cells on the surface. The in vitro result found the Fib-PLCL scaffold promoted the attachment and viability of epithelial cells on their surface. The increased expression levels of cytokeratin and actin filaments were observed in Fib-PLCL scaffold than PLCL scaffold. The in vivo urethral injury repairing potential of Fib-PLCL scaffold was evaluated using a rabbit urethral replacement model. In this study, a urethral defect was surgically excised and replaced with the Fib-PLCL and PLCL scaffolds or autograft. As expected, the animals healed well after surgery in the Fib-PLCL scaffold group, and no significant strictures were identified. As expected, the cellularized Fib/PLCL grafts have induced the luminal epithelialization, urethral smooth muscle cell remodelling, and capillary development all at the same time. Histological analysis revealed that the urothelial integrity in the Fib-PLCL group had progressed to that of a normal urothelium, with enhanced urethral tissue development. Based on the results, the present study suggests that the prepared fibrinogen-PLCL scaffold is more appropriate for urethral defect reconstruction.

Decreased VEGFA alleviates the symptoms of LPS-induced sepsis in a mouse model by inhibiting glycolysis and thereby regulating the polarization of macrophages

The immune imbalance caused by excessive inflammatory reactions is the primary cause of sepsis. Macrophages with M1 and M2 polarization states are important immune cells that regulate the balance of the inflammatory response in sepsis. Encouraging the conversion of macrophages from the M1 to the M2 type is an important strategy for relieving sepsis. Here, we demonstrated the upregulation of vascular endothelial growth factor A (VEGFA) in a mouse model of sepsis. Then, siRNA technology was applied to inhibit the expression of VEGFA in macrophages. Flow cytometry and RT‒qPCR results showed that low expression of VEGFA inhibited LPS-induced M1 polarization of macrophages. Decreased VEGFA was also proven to lower TNF-α, IL-1β, and IL-6 secretion by LPS-induced macrophages. In addition, the effects of knocking down VEGFA on the energy metabolism pattern of macrophages were investigated by glycolysis pressure tests and mitochondrial pressure tests, and VEGFA knockdown reversed the induction of glycolysis in macrophages by LPS. The mitochondrial content and ATP content results also confirmed this finding. After the tail vein of septic mice was injected with macrophages transfected with si-VEGFA, the liver and kidney damage and the pathological conditions of the lung were alleviated. The secretion of TNF-α and IL-6 was decreased, while IL-10 was increased in their serum. Immunohistochemical staining revealed decreased expression of CD86 and increased expression of CD206 in the si-VEGFA group. This study demonstrates that decreased VEGFA inhibits glycolysis and thus inhibits LPS-induced M1 polarization of macrophages, ultimately relieving sepsis.

Prospects and Challenges of Electrospun Cell and Drug Delivery Vehicles to Correct Urethral Stricture

Current therapeutic modalities to treat urethral strictures are associated with several challenges and shortcomings. Therefore, significant strides have been made to develop strategies with minimal side effects and the highest therapeutic potential. In this framework, electrospun scaffolds incorporated with various cells or bioactive agents have provided promising vistas to repair urethral defects. Due to the biomimetic nature of these constructs, they can efficiently mimic the native cells’ niches and provide essential microenvironmental cues for the safe transplantation of multiple cell types. Furthermore, these scaffolds are versatile platforms for delivering various drug molecules, growth factors, and nucleic acids. This review discusses the recent progress, applications, and challenges of electrospun scaffolds to deliver cells or bioactive agents during the urethral defect repair process. First, the current status of electrospinning in urethral tissue engineering is presented. Then, the principles of electrospinning in drug and cell delivery applications are reviewed. Finally, the recent preclinical studies are summarized and the current challenges are discussed.

Tailor-made natural and synthetic grafts for precise urethral reconstruction

Injuries to the urethra can be caused by malformations, trauma, inflammation, or carcinoma, and reconstruction of the injured urethra is still a significant challenge in clinical urology. Implanting grafts for urethroplasty and end-to-end anastomosis are typical clinical interventions for urethral injury. However, complications and high recurrence rates remain unsatisfactory. To address this, urethral tissue engineering provides a promising modality for urethral repair. Additionally, developing tailor-made biomimetic natural and synthetic grafts is of great significance for urethral reconstruction. In this work, tailor-made biomimetic natural and synthetic grafts are divided into scaffold-free and scaffolded grafts according to their structures, and the influence of different graft structures on urethral reconstruction is discussed. In addition, future development and potential clinical application strategies of future urethral reconstruction grafts are predicted.

Application of antibody-conjugated small intestine submucosa to capture urine-derived stem cells for bladder repair in a rabbit model

The need for bladder reconstruction and side effects of cystoplasty have spawned the demand for the development of alternative material substitutes. Biomaterials such as submucosa of small intestine (SIS) have been widely used as patches for bladder repair, but the outcomes are not fully satisfactory. To capture stem cells in situ has been considered as a promising strategy to speed up the process of re-cellularization and functionalization. In this study, we have developed an anti-CD29 antibody-conjugated SIS scaffold (AC-SIS) which is capable of specifically capturing urine-derived stem cells (USCs) in situ for tissue repair and regeneration. The scaffold has exhibited effective capture capacity and sound biocompatibility. In vivo experiment proved that the AC-SIS scaffold could promote rapid endothelium healing and smooth muscle regeneration. The endogenous stem cell capturing scaffolds has thereby provided a new revenue for developing effective and safer bladder patches.

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We developed an anti-CD29 antibody-crosslinked submucosa of small intestine scaffold (AC-SIS).

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AC-SIS is capable of specifically capturing urine-derived stem cells (USCs) as well as possesses a sound biocompatibility.

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AC-SIS promotes in situ tissue regeneration by facilitating the repair of bladder epithelium, smooth muscle and angiogenesis.

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Design and application of endogenous stem cell capturing scaffolds provides a new strategy for bladder repair.

Hypoxia: molecular pathophysiological mechanisms in human diseases

Hypoxia, a low O2 tension, is a fundamental feature that occurs in physiological events as well as pathophysiological conditions, especially mentioned for its role in the mechanism of angiogenesis, glucose metabolism, and cell proliferation/survival. The hypoxic state through the activation of specific mechanisms is an aggravating circumstance commonly noticed in multiple sclerosis, cancer, heart disease, kidney disease, liver disease, lung disease, and in inflammatory bowel disease. On the other hand, hypoxia could play a key role in tissue regeneration and repair of damaged tissues, especially by acting on specific tissue stem cells, but their features may result as a disadvantage when it is concerned for neoplastic stem cells. Furthermore, hypoxia could also have a potential role in tissue engineering and regenerative medicine due to its capacity to improve the performance of biomaterials. The current review aims to highlight the hypoxic molecular mechanisms reported in different pathological conditions to provide an overview of hypoxia as a therapeutic agent in regenerative and molecular therapy.

Graphical abstract

3D Printed Integrated Bionic Oxygenated Scaffold for Bone Regeneration

The repair of large bone defects remains a challenging problem in bone tissue engineering. Ischemia and hypoxia in the bone defect area make it difficult for seed cells to survive and differentiate, which fail to perform effective tissue regeneration. Current oxygen-producing materials frequently encounter problems such as a rapid degradation rate, insufficient mechanical properties, difficult molding, and cumbersome fabrication. Here, a novel three-dimensional (3D) printed integrated bionic oxygenated scaffold was fabricated with gelatin-CaO₂ microspheres, polycaprolactone (PCL), and nanohydroxyapatite (nHA) using low-temperature molding 3D printing technology. The scaffold had outstanding mechanical properties with bionic hierarchical porous structures. In vitro reports showed that the scaffold exhibited excellent cytocompatibility and could release O₂ sustainably for more than 2 weeks, which significantly enhanced the survival, growth, and osteogenic differentiation of bone marrow mesenchymal stem cells under hypoxia. In vivo experiments revealed that the scaffold facilitated efficient bone repair after it was transplanted into a rabbit calvarial defect model. This result may be due to the scaffolds reducing hypoxia-inducible factor-1α accumulation, improving the expression of osteogenic regulatory transcription factors, and accelerating osteogenesis. In summary, the integrated bionic PCL/nHA/CaO₂ scaffold had excellent capabilities in sustainable O₂ release and bone regeneration, which provided a promising clinical strategy for bone defect repair.

Constructing Tissue-Engineered Dressing Membranes with Adipose-Derived Stem Cells and Acellular Dermal Matrix for Diabetic Wound Healing: A Comparative Study of Hypoxia- or Normoxia-Culture Modes

Diabetes foot ulcer (DFU) is a serious complication of diabetes, characterized by impaired vascular function, limited angiogenesis, and chronic inflammation. Direct stem cell injection on treating DFU is far from satisfactory in clinical practice, as this therapy neither protects nor localizes the injected cell suspension at the chronic ulcer site. Meanwhile, most of injected cells gradually perished within several days due to senescence or apoptosis. Acellular dermal matrix (ADM) has the potential to act as excellent cell delivery vehicles, considering it is highly biomimetic to native dermal tissue, has low immunogenicity, and suitable for stem cell attachment and proliferation. Hypoxia culture has significantly enhanced effects on the survival ability of in vitro cultured stem cells, indicating this culture mode is a suitable way for inhibiting the senescence or apoptosis of transplanted cells. In the current study, we, respectively, culture adipose-derived stem cells (ADSCs) on an ADM membrane under a hypoxia or normoxia condition to construct two kinds of tissue-engineered dressing membranes (H-ADSCs/ADM and N-ADSCs/ADM) and then comparatively evaluated their efficacy on DFU healing using a diabetic rat model. In vitro results showed that hypoxia precondition could stimulate the ADSCs secreting VEGF-A, and the culture medium from hypoxia-preconditioned ADSCs could enhance the proliferation, migration, and angiogenesis of HUVECs. In vivo results indicated that compared to the N-ADSCs/ADM membrane, the transplanted cells in the H-ADSCs/ADM membrane can survive longer at the chronic ulcer site, consequently improve angiogenesis, inhibit inflammation, and increase extracellular matrix remodeling, eventually accelerating DFU closure. This study provides an innovative covering graft for the treatment of DFU in the clinic.

Human iPSC-Derived Vascular Smooth Muscle Cells in a Fibronectin Functionalized Collagen Hydrogel Augment Endothelial Cell Morphogenesis

Tissue-engineered constructs have immense potential as autologous grafts for wound healing. Despite the rapid advancement in fabrication technology, the major limitation is controlling angiogenesis within these constructs to form a vascular network. Here, we aimed to develop a 3D hydrogel that can regulate angiogenesis. We tested the effect of fibronectin and vascular smooth muscle cells derived from human induced pluripotent stem cells (hiPSC-VSMC) on the morphogenesis of endothelial cells. The results demonstrate that fibronectin increases the number of EC networks. However, hiPSC-VSMC in the hydrogel further substantiated the number and size of EC networks by vascular endothelial growth factor and basic fibroblast growth factor secretion. A mechanistic study shows that blocking αvβ3 integrin signaling between hiPSC-VSMC and fibronectin impacts the EC network formation via reduced cell viability and proangiogenic growth factor secretion. Collectively, this study set forth initial design criteria in developing an improved pre-vascularized construct.

Considerations for the clinical use of stem cells in genitourinary regenerative medicine

The genitourinary tract can be affected by several pathologies which require repair or replacement to recover biological functions. Current therapeutic strategies are challenged by a growing shortage of adequate tissues. Therefore, new options must be considered for the treatment of patients, with the use of stem cells (SCs) being attractive. Two different strategies can be derived from stem cell use: Cell therapy and tissue therapy, mainly through tissue engineering. The recent advances using these approaches are described in this review, with a focus on stromal/mesenchymal cells found in adipose tissue. Indeed, the accessibility, high yield at harvest as well as anti-fibrotic, immunomodulatory and proangiogenic properties make adipose-derived stromal/SCs promising alternatives to the therapies currently offered to patients. Finally, an innovative technique allowing tissue reconstruction without exogenous material, the self-assembly approach, will be presented. Despite advances, more studies are needed to translate such approaches from the bench to clinics in urology. For the 21^st century, cell and tissue therapies based on SCs are certainly the future of genitourinary regenerative medicine.

Integrin β3 targeting biomaterial preferentially promotes secretion of bFGF and viability of iPSC-derived vascular smooth muscle cells

Human-induced pluripotent stem cell-derived-vascular smooth muscle cells (hiPSC-VSMC) and their secretome have been shown to promote angiogenesis and wound healing. However, there is a paucity of research on how the extracellular matrix (ECM) microenvironment may impact the hiPSC-VSMC's functions. In this study, we investigated the effect of specific ECM ligand-integrin interaction on hiPSC-VSMC's paracrine secretion, cell viability, and morphology. Here, we show precise modulation of hiPSC-VSMC in a fibronectin functionalized fibrillar collagen scaffold by targeting their integrin β3. The secretion of proangiogenic growth factor, basic fibroblast growth factor (bFGF) was found to be fibronectin-dependent via αvβ3 integrin interactions. In addition, our data show the possible role of a positive feedback loop between integrin β3, bFGF, and matrix metalloproteinase-2 in regulating hiPSC-VSMC's morphology and cell viability. Finally, the secretome with enhanced bFGF shows potential for future wound healing applications.

Hypoxic preconditioning rejuvenates mesenchymal stem cells and enhances neuroprotection following intracerebral hemorrhage via the miR-326-mediated autophagy

BACKGROUND

Intracerebral hemorrhage (ICH) is a major public health concern, and mesenchymal stem cells (MSCs) hold great potential for treating ICH. However, the quantity and quality of MSCs decline in the cerebral niche, limiting the potential efficacy of MSCs. Hypoxic preconditioning is suggested to enhance the survival of MSCs and augment the therapeutic efficacy of MSCs in ICH. MicroRNAs (miRNAs) are known to mediate cellular senescence. However, the precise mechanism by which miRNAs regulate the senescence of hypoxic MSCs remains to be further studied. In the present study, we evaluated whether hypoxic preconditioning enhances the survival and therapeutic effects of olfactory mucosa MSC (OM-MSC) survival and therapeutic effects in ICH and investigated the mechanisms by which miRNA ameliorates hypoxic OM-MSC senescence.

METHODS

In the in vivo model, ICH was induced in mice by administration of collagenase IV. At 24 h post-ICH, 5 × 10⁵ normoxia or hypoxia OM-MSCs or saline was administered intracerebrally. The behavioral outcome, neuronal apoptosis, and OM-MSC survival were evaluated. In the in vitro model, OM-MSCs were exposed to hemin. Cellular senescence was examined by evaluating the expressions of P16INK4A, P21, P53, and by β-galactosidase staining. Microarray and bioinformatic analyses were performed to investigate the differences in the miRNA expression profiles between the normoxia and hypoxia OM-MSCs. Autophagy was confirmed using the protein expression levels of LC3, P62, and Beclin-1.

RESULTS

In the in vivo model, transplanted OM-MSCs with hypoxic preconditioning exhibited increased survival and tissue-protective capability. In the in vitro model, hypoxia preconditioning decreased the senescence of OM-MSCs exposed to hemin. Bioinformatic analysis identified that microRNA-326 (miR-326) expression was significantly increased in the hypoxia OM-MSCs compared with that of normoxia OM-MSCs. Upregulation of miR-326 alleviated normoxia OM-MSC senescence, whereas miR-326 downregulation increased hypoxia OM-MSC senescence. Furthermore, we showed that miR-326 alleviated cellular senescence by upregulating autophagy. Mechanistically, miR-326 promoted the autophagy of OM-MSCs via the PI3K signaling pathway by targeting polypyrimidine tract-binding protein 1 (PTBP1).

CONCLUSIONS

Our study shows that hypoxic preconditioning delays OM-MSC senescence and augments the therapeutic efficacy of OM-MSCs in ICH by upregulating the miR-326/PTBP1/PI3K-mediated autophagy.