A sustained release of BMP2 in urine-derived stem cells enhances the osteogenic differentiation and the potential of bone regeneration

Urine-derived stem cells: Promising advancements and applications in regenerative medicine and beyond

Currently, stem cells are a prominent focus of regenerative engineering research. However, due to the limitations of commonly used stem cell sources, their application in therapy is often restricted to the experimental stage and constrained by ethical considerations. In contrast, urine-derived stem cells (USCs) offer promising advantages for clinical trials and applications. The noninvasive nature of the collection process allows for repeated retrieval within a short period, making it a more feasible option. Moreover, studies have shown that USCs have a protective effect on organs, promoting vascular regeneration, inhibiting oxidative stress, and reducing inflammation in various acute and chronic organ dysfunctions. The application of USCs has also been enhanced by advancements in biomaterials technology, enabling better targeting and controlled release capabilities. This review aims to summarize the current state of research on USCs, providing insights for future applications in basic and clinical settings.

Immediate implantation of ultrafine fiber slow-release system based on cell electrospinning to induce osteogenesis of mesenchymal stem cells

This study presents the development and evaluation of a poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) ultrafine fiber slow-release system for in vivo osteogenic induction of human umbilical cord mesenchymal stem cells (HUCMSCs). Utilizing dual-nozzle and cell electrospinning techniques, the system encapsulates L-ascorbic acid-2-phosphate magnesium (ASP), β-glycerophosphate sodium and dexamethasone (DEX) within the fibers, ensuring sustained osteogenic differentiation. The scaffold's morphology, characterization, hydrophilicity, mechanical properties and cellular behavior were examined. Immediate subcutaneous implantation in rabbits was conducted to observe its ectopic osteogenic induction effect. Successfully fabricated P34HB ultrafine fiber slow-release system. Characterization confirmed the uniform distribution of HUCMSCs and inducing components within the scaffold, with no chemical reactions affecting the active components. In vitro tests showcased a prolonged release of DEX and ASP, while biocompatibility assays highlighted the scaffold's suitability for cellular growth. Alizarin Red, type I collagen, and osteopontin (OPN) staining verified the scaffold's potent osteogenic induction effect on HUCMSCs. Notably, immediate implantation into New Zealand White rabbits led to significant new bone formation within 8 weeks. These findings underscore the system's potential for immediate in vivo implantation without prior in vitro induction, marking a promising advancement in bone tissue engineering.

A construct of adipose-derived mesenchymal stem cells-laden collagen scaffold for fertility restoration by inhibiting fibrosis in a rat model of endometrial injury

Severe endometrium damage causes pathological conditions such as thin endometrium and intrauterine adhesion, resulting in uterine factor infertility. Mesenchymal stem cell (MSC) therapy is a promising strategy in endometrial repair; yet, exogenous MSCs still raise concerns for safety and ethical issues. Human adipose-derived mesenchymal stem cells (ADMSCs) residing in adipose tissue have high translational potentials due to their autologous origin. To harness the high translation potentials of ADMSC in clinical endometrium regeneration, here we constructed an ADMSCs composited porous scaffold (CS/ADMSC) and evaluated its effectiveness on endometrial regeneration in a rat endometrium-injury model. We found that CS/ADMSC intrauterine implantation (i) promoted endometrial thickness and gland number, (ii) enhanced tissue angiogenesis, (iii) reduced fibrosis and (iv) restored fertility. We ascertained the pro-proliferation, pro-angiogenesis, immunomodulating and anti-fibrotic effects of CS/ADMSC in vitro and revealed that the CS/ADMSC influenced extracellular matrix composition and organization by a transcriptomic analysis. Our results demonstrated the effectiveness of CS/ADMSC for endometrial regeneration and provided solid proof for our future clinical study.

Sequential deacetylation/self-gelling chitin hydrogels and scaffolds functionalized with fucoidan for enhanced BMP-2 loading and sustained release

Bone morphogenetic protein 2 (BMP-2) is a potent osteoinductive factor that promotes bone formation. A major obstacle to the clinical application of BMP-2 is its inherent instability and complications caused by its rapid release from implants. Chitin based materials have excellent biocompatibility and mechanical properties, making them ideal for bone tissue engineering applications. In this study, a simple and easy method was developed to spontaneously form deacetylated β-chitin (DAC-β-chitin) gels at room temperature through a sequential deacetylation/self-gelation process. The structural transformation of β-chitin to DAC-β-chitin leads to the formation of self-gelling DAC-β-chitin, from which hydrogels and scaffolds were prepared. Gelatin (GLT) accelerated the self-gelation of DAC-β-chitin and increased the pore size and porosity of the DAC-β-chitin scaffold. The DAC-β-chitin scaffolds were then functionalized with a BMP-2-binding sulfate polysaccharide, fucoidan (FD). Compared with β-chitin scaffolds, FD-functionalized DAC-β-chitin scaffolds showed higher BMP-2 loading capacity and more sustainable release of BMP-2, and thus had better osteogenic activity for bone regeneration.

Recent advances in regenerative biomaterials

Nowadays, biomaterials have evolved from the inert supports or functional substitutes to the bioactive materials able to trigger or promote the regenerative potential of tissues. The interdisciplinary progress has broadened the definition of 'biomaterials', and a typical new insight is the concept of tissue induction biomaterials. The term 'regenerative biomaterials' and thus the contents of this article are relevant to yet beyond tissue induction biomaterials. This review summarizes the recent progress of medical materials including metals, ceramics, hydrogels, other polymers and bio-derived materials. As the application aspects are concerned, this article introduces regenerative biomaterials for bone and cartilage regeneration, cardiovascular repair, 3D bioprinting, wound healing and medical cosmetology. Cell-biomaterial interactions are highlighted. Since the global pandemic of coronavirus disease 2019, the review particularly mentions biomaterials for public health emergency. In the last section, perspectives are suggested: (i) creation of new materials is the source of innovation; (ii) modification of existing materials is an effective strategy for performance improvement; (iii) biomaterial degradation and tissue regeneration are required to be harmonious with each other; (iv) host responses can significantly influence the clinical outcomes; (v) the long-term outcomes should be paid more attention to; (vi) the noninvasive approaches for monitoring in vivo dynamic evolution are required to be developed; (vii) public health emergencies call for more research and development of biomaterials; and (viii) clinical translation needs to be pushed forward in a full-chain way. In the future, more new insights are expected to be shed into the brilliant field-regenerative biomaterials.

Nanotopographical 3D-Printed Poly(ε-caprolactone) Scaffolds Enhance Proliferation and Osteogenic Differentiation of Urine-Derived Stem Cells for Bone Regeneration

3D-printing technology can be used to construct personalized bone substitutes with customized shapes, but it cannot regulate the topological morphology of the scaffold surface, which plays a vital role in regulating the biological behaviors of stem cells. In addition, stem cells are able to sense the topographical and mechanical cues of surface of scaffolds by mechanosensing and mechanotransduction. In our study, we fabricated a 3D-printed poly(ε-caprolactone) (PCL) scaffold with a nanotopographical surface and loaded it with urine-derived stem cells (USCs) for application of bone regeneration. The topological 3D-printed PCL scaffolds (TPS) fabricated by surface epiphytic crystallization, possessed uniformly patterned nanoridges, of which the element composition and functional groups of nanoridges were the same as PCL. Compared with bare 3D-printed PCL scaffolds (BPS), TPS have a higher ability for protein adsorption and mineralization in vitro. The proliferation, cell length, and osteogenic gene expression of USCs on the surface of TPS were significantly higher than that of BPS. In addition, the TPS loaded with USCs exhibited a good ability for bone regeneration in cranial bone defects. Our study demonstrated that nanotopographical 3D-printed scaffolds loaded with USCs are a safe and effective therapeutic strategy for bone regeneration.