Promotion of uterine reconstruction by a tissue-engineered uterus with biomimetic structure and extracellular matrix microenvironment.

The recurrence rate for severe intrauterine adhesions is as high as 60%, and there is still lack of effective prevention and treatment. Inspired by the nature of uterus, we have developed a bilayer scaffold (ECM-SPS) with biomimetic heterogeneous features and extracellular matrix (ECM) microenvironment of the uterus. As proved by subtotal uterine reconstruction experiments, the mechanical and antiadhesion properties of the bilayer scaffold could meet the requirement for uterine repair. With the modification with tissue-specific cell-derived ECM, the ECM-SPS had the ECM microenvironment signatures of both the endometrium and myometrium and exhibited the property of inducing stem cell-directed differentiation. Furthermore, the ECM-SPS has recruited more endogenous stem cells to promote endometrial regeneration at the initial stage of repair, which was accompanied by more smooth muscle regeneration and a higher pregnancy rate. The reconstructed uterus could also sustain normal pregnancy and live birth. The ECM-SPS may thereby provide a potential treatment for women with severe intrauterine adhesions.

Emerging Bioactive Agent Delivery-Based Regenerative Therapies for Lower Genitourinary Tissues.

Injury to lower genitourinary (GU) tissues, which may result in either infertility and/or organ dysfunctions, threatens the overall health of humans. Bioactive agent-based regenerative therapy is a promising therapeutic method. However, strategies for spatiotemporal delivery of bioactive agents with optimal stability, activity, and tunable delivery for effective sustained disease management are still in need and present challenges. In this review, we present the advancements of the pivotal components in delivery systems, including biomedical innovations, system fabrication methods, and loading strategies, which may improve the performance of delivery systems for better regenerative effects. We also review the most recent developments in the application of these technologies, and the potential for delivery-based regenerative therapies to treat lower GU injuries. Recent progress suggests that the use of advanced strategies have not only made it possible to develop better and more diverse functionalities, but also more precise, and smarter bioactive agent delivery systems for regenerative therapy. Their application in lower GU injury treatment has achieved certain effects in both patients with lower genitourinary injuries and/or in model animals. The continuous evolution of biomaterials and therapeutic agents, advances in three-dimensional printing, as well as emerging techniques all show a promising future for the treatment of lower GU-related disorders and dysfunctions.

The effect of age and abstinence time on semen quality: a retrospective study.

This study analyzed the effects of male age and abstinence time on semen quality and explored the best abstinence time for Chinese males among different age groups. Semen parameters, including sperm kinetics, morphology, and DNA fragmentation index (DFI), were reviewed from 2952 men. Samples were divided into six age groups (≤25 years, 26-30 years, 31-35 years, 36-40 years, 41-45 years, and >45 years) and were divided into six groups according to different abstinence time (2 days, 3 days, 4 days, 5 days, 6 days, and 7 days). The differences in semen quality between the groups were compared, and the effect of age and abstinence time on semen quality was analyzed. Significant differences were observed in semen volume, progressive motility (PR), and DFI among the age groups (all P < 0.05), and no significant differences were observed in sperm morphological parameters (all P > 0.05). There were significant differences in semen volume, PR, and DFI among different abstinence time groups (all P < 0.05) and no significant differences in sperm morphological parameters (all P > 0.05). Pearson analysis showed that male age and abstinence time were both significantly correlated with sperm kinetics and DFI (both P < 0.05), while no significant correlation was found with sperm morphological parameters (all P > 0.05). The box plots and histograms of men's age, abstinence time, and semen quality show that most semen quality parameters differ significantly between the 2 days and 7 days abstinence groups and other groups at different ages. Except for the sperm morphology parameters, sperm kinetic parameters and sperm DFI are linearly related to male age and abstinence time.

Membranous Extracellular Matrix-Based Scaffolds for Skin Wound Healing.

Membranous extracellular matrix (ECM)-based scaffolds are one of the most promising biomaterials for skin wound healing, some of which, such as acellular dermal matrix, small intestinal submucosa, and amniotic membrane, have been clinically applied to treat chronic wounds with acceptable outcomes. Nevertheless, the wide clinical applications are always hindered by the poor mechanical properties, the uncontrollable degradation, and other factors after implantation. To highlight the feasible strategies to overcome the limitations, in this review, we first outline the current clinical use of traditional membranous ECM scaffolds for skin wound healing and briefly introduce the possible repair mechanisms; then, we discuss their potential limitations and further summarize recent advances in the scaffold modification and fabrication technologies that have been applied to engineer new ECM-based membranes. With the development of scaffold modification approaches, nanotechnology and material manufacturing techniques, various types of advanced ECM-based membranes have been reported in the literature. Importantly, they possess much better properties for skin wound healing, and would become promising candidates for future clinical translation.

Mesenchymal Stem Cells for Chronic Wound Healing: Current Status of Preclinical and Clinical Studies.

Healing skin wounds with anatomic and functional integrity, especially under chronic pathological conditions, remain an enormous challenge. Due to their outstanding regenerative potential, mesenchymal stem cells (MSCs) have been explored in many studies to determine the healing ability for difficult-to-treat diseases. In this article, we review current animal studies and clinical trials of MSC-based therapy for chronic wounds, and discuss major challenges that confront future clinical applications. We found that a wealth of animal studies have revealed the versatile roles and the benefits of MSCs for chronic wound healing. MSC treatment results in enhanced angiogenesis, facilitated reepithelialization, improved granulation, and accelerated wound closure. There are some evidences of the transdifferentiation of MSCs into skin cells. However, the healing effect of MSCs depends primarily on their paracrine actions, which alleviate the harsh microenvironment of chronic wounds and regulate local cellular responses. Consistent with the findings of preclinical studies, some clinical trials have shown improved wound healing after transplantation of MSCs in chronic wounds, mainly lower extremity ulcers, pressure sores, and radiation burns. However, there are some limitations in these clinical trials, especially a small number of patients and imperfect methodology. Therefore, to better define the safety and efficiency of MSC-based wound therapy, large-scale controlled multicenter trials are needed in the future. In addition, to build a robust pool of clinical evidence, standardized protocols, especially the cultivation and quality control of MSCs, are recommended. Altogether, based on current data, MSC-based therapy represents a promising treatment option for chronic wounds. Impact statement Chronic wounds persist as a significant health care problem, particularly with increasing number of patients and the lack of efficient treatments. The main goal of this article is to provide an overview of current status of mesenchymal stem cell (MSC)-based therapy for chronic wounds. The roles of MSCs in skin wound healing, as revealed in a large number of animal studies, are detailed. A critical view is made on the clinical application of MSCs for lower extremity ulcers, pressure sores, and radiation burns. Main challenges that confront future clinical applications are discussed, which hopefully contribute to innovations in MSC-based wound treatment.

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.

Progress in development of bioderived materials for dermal wound healing.

Treatment of acute and chronic wounds is one of the primary challenges faced by doctors. Bioderived materials have significant potential clinical value in tissue injury treatment and defect reconstruction. Various strategies, including drug loading, addition of metallic element(s), cross-linking and combining two or more distinct types of materials with complementary features, have been used to synthesize more suitable materials for wound healing. In this review, we describe the recent developments made in the processing of bioderived materials employed for cutaneous wound healing, including newly developed materials such as keratin and soy protein. The focus was on the key properties of the bioderived materials that have shown great promise in improving wound healing, restoration and reconstruction. With their good biocompatibility, nontoxic catabolites, microinflammation characteristics, as well as their ability to induce tissue regeneration and reparation, the bioderived materials have great potential for skin tissue repair.

Tissue engineered esophagus scaffold constructed with porcine small intestinal submucosa and synthetic polymers.

Acellular porcine small intestinal submucosa (SIS) has been successfully used for reconstructing esophagus with half circumferential defects. However, repairing full circumferential esophageal defects with SIS has been restricted due to the latter's poor mechanical properties. In the present study, synthetic polyesters biomaterial poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(lactide-co-glycolide) (PLGA) have been used to improve the mechanical properties of SIS. Feasibility of SIS/PHBHHx-PLGA composite material scaffold for esophageal tissue engineering has been assessed through a series of testing. The appropriate mixing ratio of PHBHHx and PLGA polymers has been determined as 5:5 by mechanical testing and in vitro degradation experiment. The morphology of constructed membranous and tubular scaffolds was also characterized. As confirmed by enzyme-linked immunosorbent assay, the contents of VEGF and TGF-ß have respectively reached 657 ± 18 ng mL(-1) and 130 ± 4 pg mL(-1) within the SIS/PHBHHx-PLGA specimens. Biocompatibility of the SIS/PHBHHx-PLGA specimens with rat bone marrow mesenchymal stem cells (MSCs) was also evaluated by scanning electron microscopy and a live-dead cell viability assay. Actin filaments of MSCs on the composite materials were labeled. Biological safety of the extract from SIS/PHBHHx-PLGA specimens, measured as hemolysis rate, was all lower than 5%. Compared with SIS and SIS/PHBHHx-PLGA specimens, inflammatory reaction provoked by the PHBHHx-PLGA specimens in rats was however more severe. Our results have suggested that SIS/PHBHHx-PLGA composite material can offer a new approach for esophageal tissue engineering.