Hydrogel-exosome system in tissue engineering: A promising therapeutic strategy.

Characterized by their pivotal roles in cell-to-cell communication, cell proliferation, and immune regulation during tissue repair, exosomes have emerged as a promising avenue for "cell-free therapy" in clinical applications. Hydrogels, possessing commendable biocompatibility, degradability, adjustability, and physical properties akin to biological tissues, have also found extensive utility in tissue engineering and regenerative repair. The synergistic combination of exosomes and hydrogels holds the potential not only to enhance the efficiency of exosomes but also to collaboratively advance the tissue repair process. This review has summarized the advancements made over the past decade in the research of hydrogel-exosome systems for regenerating various tissues including skin, bone, cartilage, nerves and tendons, with a focus on the methods for encapsulating and releasing exosomes within the hydrogels. It has also critically examined the gaps and limitations in current research, whilst proposed future directions and potential applications of this innovative approach.

Bioactive ECM-Loaded SIS Generated by the Optimized Decellularization Process Exhibits Skin Wound Healing Ability in Type I Diabetic Rats.

Patients with diabetes have 15-25% chance for developing diabetic ulcers as a severe complication and formidable challenge for clinicians. Conventional treatment for diabetic ulcers is to surgically remove the necrotic skin, clean the wound, and cover it with skin flaps. However, skin flap often has a limited efficacy, and its acquisition requires a second surgery, which may bring additional risk for the patient. Skin tissue engineering has brought a new solution for diabetic ulcers. Herein, we have developed a bioactive patch through a compound culture and the optimized decellularization strategy. The patch was prepared from porcine small intestinal submucosa (SIS) and modified by an extracellular matrix (ECM) derived from urine-derived stem cells (USCs), which have low immunogenicity while retaining cytokines for angiogenesis and tissue regeneration. The protocol included the optimization of the decellularization time and the establishment of the methods. Furthermore, the in vitro mechanism of wound healing ability of the patch was investigated, and its feasibility for skin wound healing was assessed through an antishrinkage full-thickness skin defect model in type I diabetic rats. As shown, the patch displayed comparable effectiveness to the USCs-loaded SIS. Our findings suggested that this optimized decellularization protocol may provide a strategy for cell-loaded scaffolds that require the removal of cellular material while retaining sufficient bioactive components in the ECM for further applications.

SIGIRR deficiency contributes to CD4 T cell abnormalities by facilitating the IL1/C/EBPß/TNF-α signaling axis in rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a complex autoimmune disease with multiple etiological factors, among which aberrant memory CD4 T cells activation plays a key role in the initiation and perpetuation of the disease. SIGIRR (single immunoglobulin IL-1R-related receptor), a member of the IL-1 receptor (ILR) family, acts as a negative regulator of ILR and Toll-like receptor (TLR) downstream signaling pathways and inflammation. The aim of this study was to investigate the potential roles of SIGIRR on memory CD4 T cells in RA and the underlying cellular and molecular mechanisms. METHODS: Single-cell transcriptomics and bulk RNA sequencing data were integrated to predict SIGIRR gene distribution on different immune cell types of human PBMCs. Flow cytometry was employed to determine the differential expression of SIGIRR on memory CD4 T cells between the healthy and RA cohorts. A Spearman correlation study was used to determine the relationship between the percentage of SIGIRR+ memory CD4 T cells and RA disease activity. An AIA mouse model (antigen-induced arthritis) and CD4 T cells transfer experiments were performed to investigate the effect of SIGIRR deficiency on the development of arthritis in vivo. Overexpression of SIGIRR in memory CD4 T cells derived from human PBMCs or mouse spleens was utilized to confirm the roles of SIGIRR in the intracellular cytokine production of memory CD4 T cells. Immunoblots and RNA interference were employed to understand the molecular mechanism by which SIGIRR regulates TNF-α production in CD4 T cells. RESULTS: SIGIRR was preferentially distributed by human memory CD4 T cells, as revealed by single-cell RNA sequencing. SIGIRR expression was substantially reduced in RA patient-derived memory CD4 T cells, which was inversely associated with RA disease activity and related to enhanced TNF-α production. SIGIRR-deficient mice were more susceptible to antigen-induced arthritis (AIA), which was attributed to unleashed TNF-α production in memory CD4 T cells, confirmed by decreased TNF-α production resulting from ectopic expression of SIGIRR. Mechanistically, SIGIRR regulates the IL-1/C/EBPß/TNF-α signaling axis, as established by experimental evidence and cis-acting factor bioinformatics analysis. CONCLUSION: Taken together, SIGIRR deficiency in memory CD4 T cells in RA raises the possibility that receptor induction can target key abnormalities in T cells and represents a potentially novel strategy for immunomodulatory therapy.

Saikosaponin D Alleviates DOX-induced Cardiac Injury In Vivo and In Vitro.

ABSTRACT: As a highly efficient anticancer agent, doxorubicin (DOX) is used for treatment of various cancers, but DOX-induced oxidative damages contribute to a degenerative irreversible cardiac toxicity. Saikosaponin D (SSD), which is a triterpenoid saponin with many biological activities including anti-inflammatory effects and antioxidant properties, provides protection against pathologic cardiac remodeling and fibrosis. In the present study, we investigated the work of SSD for DOX-induced cardiotoxicity and the involved mechanisms. We observed that DOX injection induced cardiac injury and malfunction and decreased survival rate. Besides, DOX treatment increased lactate dehydrogenase leakage, cardiomyocyte apoptosis, and myocardium fibrosis and decreased the size of cardiomyocytes. Meanwhile, all the effects were notably attenuated by SSD treatment. In vitro, we found that 1 µM SSD could enhance the proliferation of H9c2 cells and inhibit DOX-induced apoptosis. It was found that the levels of malondialdehyde (MDA) and reactive oxygen species were significantly reduced by improving the activities of the endogenous antioxidative enzymes including catalase and glutathione peroxidase. Furthermore, SSD treatment could downregulate the DOX-induced p38 phosphorylation. Our results suggested that SSD efficiently protected the cardiomyocytes from DOX-induced cardiotoxicity by inhibiting the excessive oxidative stress via p38-MAPK (mitogen-activated protein kinase, MAPK) signaling pathway.

Accelerating ESD-induced gastric ulcer healing using a pH-responsive polyurethane/small intestinal submucosa hydrogel delivered by endoscopic catheter.

Endoscopic submucosal dissection (ESD) is the standard treatment for early-stage gastric cancer, but the large post-operative ulcers caused by ESD often lead to serious side effects. Post-ESD mucosal repair materials provide a new option for the treatment of post-ESD ulcers. In this study, we developed a polyurethane/small intestinal submucosa (PU/SIS) hydrogel and investigated its efficacy for accelerating ESD-induced ulcer healing in a canine model. PU/SIS hydrogel possessed great biocompatibility and distinctive pH-sensitive swelling properties and protected GES-1 cells from acid attack through forming a dense film in acidic conditions in vitro. Besides, PU/SIS gels present a strong bio-adhesion to gastric tissues under acidic conditions, thus ensuring the retention time of PU/SIS gels in vivo. In a canine model, PU/SIS hydrogel was easily delivered via endoscopy and adhered to the ulcer sites. PU/SIS hydrogel accelerated gastric ulcer healing at an early stage with more epithelium regeneration and slight inflammation. Our findings reveal PU/SIS hydrogel is a promising and attractive candidate for ESD-induced ulcer repair.

Establishing Standardized Biomedical Laboratory Technician Education for the Development of Biotechnology Research in China.

Chinese scientists have been actively engaged in biotechnology research since the mid-20th century. However, biotechnology education, especially biomedical laboratory technology education, is relatively scarce in China. More and more cutting-edge equipment and techniques have been introduced into biomedical laboratories in China, but there is a lack of high-quality technicians to apply these advancements to scientific research. In addition, the traditional education and apprenticeship systems have been demonstrated little progress. To address this gap, West China Hospital of Sichuan University established a 2-year educational program for laboratory technology in 2006 based on the residency training program. The project integrates scientific methods into the research laboratory technician training in relevant disciplines, and has developed a systematic, scientific, and effective standardized training system to cultivate high-level and stable experimental technician team for the need of advanced laboratories, which has been demonstrated greatly improve the efficiency of biomedical researchers and laboratory facilities. In this article, we introduce the practical experience in establishment and development of a standardized training system for biomedical laboratory technicians to ensure the sustainable development of medical researches.

Hypoxic preconditioning of human urine-derived stem cell-laden small intestinal submucosa enhances wound healing potential.

BACKGROUND: Urine-derived stem cells (USCs) are a valuable stem cell source for tissue engineering because they can be harvested non-invasively. Small intestine submucosa (SIS) has been used as scaffolds for soft tissue repair in the clinic. However, the feasibility and efficacy of a combination of USCs and SIS for skin wound healing has not been reported. In this study, we created a tissue-engineered skin graft, termed the SIS+USC composite, and hypothesized that hypoxic preconditioning would improve its wound healing potential. METHODS: USCs were seeded on SIS membranes to fabricate the SIS+USC composites, which were then cultured in normoxia (21% O2) or preconditioned in hypoxia (1% O2) for 24 h, respectively. The viability and morphology of USCs, the expression of genes related to wound angiogenesis and reepithelialization, and the secretion of growth factors were determined in vitro. The wound healing ability of the SIS+USC composites was evaluated in a mouse full-thickness skin wound model. RESULTS: USCs showed good cell viability and morphology in both normoxia and hypoxic preconditioning groups. In vitro, hypoxic preconditioning enhanced not only the expression of genes related to wound angiogenesis (VEGF and Ang-2) and reepithelialization (bFGF and EGF) but also the secretion of growth factors (VEGF, EGF, and bFGF). In vivo, hypoxic preconditioning significantly improved the wound healing potential of the SIS+USC composites. It enhanced wound angiogenesis at the early stage of wound healing, promoted reepithelialization, and improved the deposition and remodeling of collagen fibers at the late stage of wound healing. CONCLUSIONS: Taken together, this study shows that hypoxic preconditioning provides an easy and efficient strategy to enhance the wound healing potential of the SIS+USC composite.

Identification and characterization of two morphologically distinct stem cell subpopulations from human urine samples.

Urine-derived stem cells (USCs) have shown potentials for the treatment of skeletal and urological disorders. Based on published literature and our own data, USCs consist of heterogeneous populations of cells. In this paper, we identify and characterize two morphologically distinct subpopulations of USCs from human urine samples, named as spindle-shaped USCs (SS-USCs) and rice-shaped USCs (RS-USCs) respectively. The two subpopulations showed similar clone-forming efficiency, while SS-USCs featured faster proliferation, higher motility, and greater potential for osteogenic and adipogenic differentiation, RS-USCs showed greater potential for chondrogenic differentiation. POU5F1 was strongly expressed in both subpopulations, but MYC was weakly expressed. Both subpopulations showed similar patterns of CD24, CD29, CD34, CD44, CD73, CD90 and CD105 expression, while a higher percentage of RS-USCs were positive for CD133. SS-USCs were positive for VIM, weakly positive for SLC12A1 and UMOD, and negative for KRT18, NPHS1, AQP1 and AQP2, indicating a renal mesenchyme origin; while RS-USCs are positive for VIM, partially positive for KRT18, NPHS1, AQP1, SLC12A1 and UMOD, and negative for AQP2, indicating a nephron tubule origin. The above results can facilitate understanding of the biological characteristics of subpopulations of USCs, and provide a basis for further research and applications of such cells.

Nanostructured titanium surfaces fabricated by hydrothermal method: Influence of alkali conditions on the osteogenic performance of implants.

Hydrothermal method is an easy-to-use approach for creating nanostructured surfaces on titanium (Ti). However, whether the alkali conditions of this method influence the osteogenic potential of the modified surfaces remains unknown. In this study, we fabricated nanostructured surfaces, termed the Ti-1, Ti-5, and Ti-10 groups, by using the hydrothermal method in 1 M, 5 M, and 10 M NaOH aqueous solutions, respectively. An untreated Ti surface served as a control. The osteogenic performance of modified surfaces was systemically investigated, including the proliferation and osteogenic differentiation of human osteoblast-like MG63 cells in vitro and the osteointegration of implants in a rabbit femoral condyle defect model. After hydrothermal treatment, the hydrophilicity of modified surfaces was greatly enhanced. The Ti-1 group showed a nanowire-like topography, while the Ti-5 and Ti-10 groups exhibited a nanopetal-like topography with different pore sizes. Compared with the untreated Ti surface, the modified surfaces showed good cytocompatibility and enhanced the osteogenic differentiation of MG-63 cells. Compared with the other modified surfaces, the Ti-5 group was the most favourable for the osteogenic differentiation of cells, showing higher levels of alkaline phosphatase activity, osteogenic gene expression, mineralization and osteoprotegerin secretion. Twelve weeks after implantation at the bone defects, the Ti-5 group showed superior peri-implant bone regeneration and higher peak push-out force than the other groups. Overall, this study revealed the crucial role of alkali conditions of hydrothermal method in modulating the material characteristics of modified surfaces and their osteogenic performance in vitro and in vivo, highlighting the need for optimizing the processing conditions of hydrothermal method for enhanced osteointegration.

Collagen Hydrogel Functionalized with Collagen-Targeting IFNA2b Shows Apoptotic Activity in Nude Mice with Xenografted Tumors.

Interferon alpha 2b (IFNA2b) has been used in immunotherapy for cancers with certain success. To reduce fast diffusion of IFNA2b and consequent dose-dependent side effects, we constructed a collagen hydrogel loaded with IFNA2b fused to collagen-binding domain by using methods of tissue engineering. The fusion protein showed apoptotic activity similar to that of native IFNA2b against MCF-7 cells in vitro, but with relatively higher affinity for collagen type I. Accordingly, the former diffused out of the collagen matrix slower than the latter. Importantly, collagen hydrogels loaded with the fusion protein possessed apoptotic activity in vitro and released the engineered cytokine in a controlled manner. In addition, such hydrogels reduced tumor size and extended the survival of the mouse model with xenografted tumors, which suggested a moderate antitumor activity in vivo.

Comparison of small intestinal submucosa and polypropylene mesh for abdominal wall defect repair.

Abdominal wall defects are a common medical problem, and inadequate repair methods can lead to serious complications. Abdominal wall reconstruction using autologous tissue, or non-biological, biological, or composite patches is often performed to repair defective areas. In particular, composite patches containing both polymeric and biological materials have gained increasing attention due to their good mechanical properties and biocompatibility. However, it is still unclear whether the quality of repairs using composite patches is superior to that of a biological patch. Based on the limitations of previous studies, we compared small intestinal submucosa (SIS) patches with SIS + polypropylene mesh (PPM) patches for repairing abdominal wall defects in adult beagle dogs. Forty-five female dogs were subjected to surgical resection to produce abdominal wall defects. SIS or SIS + PPM was used as patch for the defects. Morphology, biomechanics, and histological evaluations were performed to evaluate the efficacy and safety of such therapies. Our findings demonstrated that SIS had advantages over SIS + PPM considering biological activity and histocompatibility without increasing the risk of repair failure.