Tissue engineering and regenerative medicine最新文献

Background: Induced pluripotent stem cells (iPSCs) represent a promising source for regenerative therapies, yet allogeneic transplantation is limited by immune rejection. While strategies for generating hypoimmune iPSCs have been proposed, their efficacy after differentiation into lineage-specific cell types remains underexplored.

Methods: A human iPSC line (36A) from peripheral blood mononuclear cells using a Sendai virus-based reprogramming protocol. Hypoimmune properties were conferred via CRISPR-Cpf1-mediated B2M knockout, combined with lentiviral overexpression of HLA-E and CD47. Immune evasion was validated using NK cell cytotoxicity assays. Endothelial differentiation was induced using a defined, stepwise protocol, and in vivo functionality was evaluated in humanized NSG mice.

Results: The hypoimmune iPSCs retained pluripotency, exhibited stable karyotype, and demonstrated > 99% expression of HLA-E/CD47. NK cell-mediated lysis was significantly reduced in edited cells, although IFN-γ levels remained elevated. Upon differentiation, the hypoimmune iPSCs yielded > 98% CD31⁺CD144⁺ endothelial cells, which showed enhanced survival in vivo compared to wild-type controls.

Conclusion: Multiplex gene editing successfully conferred durable immune evasion in both undifferentiated and endothelial-differentiated iPSCs. These findings support the clinical potential of hypoimmune iPSC-derived cell therapies for allogeneic transplantation without immunosuppression.

Background: The human spine relies on intervertebral discs (IVDs) for support and mobility, functioning as shock absorbers that enable friction-free movement. However, IVDs are susceptible to degeneration (IVDD) due to age, excessive strain, and genetic factors, resulting in bulging or herniation that causes pain, stiffness, and nerve compression.

Current treatments: Current treatments primarily focus on symptom management through medication, physical therapy, or surgery in severe cases, without addressing tissue repair.

Emerging therapies: Exosome therapy has recently emerged as a promising regenerative approach for IVDD. Exosomes are small, membrane-bound vesicles released by cells, acting as messengers to transport proteins and RNA that influence recipient cell behavior.

Potential and challenges: Researchers are investigating exosomes for IVDD because they may promote disc repair and regeneration by delivering molecules that stimulate tissue recovery and carry anti-inflammatory agents to reduce inflammation and modulate pain. Engineering strategies, such as loading exosomes with therapeutic cargo or targeting molecules, can further enhance their efficacy. While exosome therapy for IVDD is still in early research stages, ongoing studies are promising, though challenges remain in optimizing isolation methods and ensuring clinical safety.

Conclusion: Exosome-based therapies could offer a safe, effective, and minimally invasive solution for individuals affected by IVDD.

Background: Acellular bi-layer silk fibroin (BLSF) scaffolds represent potential alternatives to autologous tissue grafts for substitution urethroplasty (SU) given their ability to repair focal urethral defects in animal models. However, in patients with a severe fibrotic urethral plate, single or staged SU are often required to restore organ continuity. Currently, the feasibility of tubular BLSF grafts for urethral replacement is unknown. Therefore, the objective of this study was to evaluate the efficacy of BLSF biomaterials for SU using single and staged approaches.

Methods: Single (N = 4) and staged (N = 5) SU with BLSF grafts were carried out in adult male rabbits, and animals were maintained for 3 months. Nonsurgical control animals (NSC, N = 3) were evaluated in parallel.

Results: All rabbits survived until harvest and displayed voluntary voiding after initial catheterization with no evidence of severe complications. At 3 months, retrograde urethrograms revealed relative urethral calibers treated with both single and staged approaches were restored to 80 ± 26% and 129 ± 27% of NSC levels. In addition, staged SU led to significantly higher degrees of scaffold degradation as well as urethral patency in respect to the single stage repairs. Histological and immunohistochemical evaluations demonstrated that both surgical techniques supported the formation of innervated, vascularized neotissues resembling NSC. However, neotissues from single stage repairs presented with elevated levels of fibrosis and reduced smooth muscle relative to NSC and the staged cohort.

Conclusions: Single and staged SU with BLSF grafts are feasible for tubular urethral replacement, but staged reconstruction results in improved functional tissue regeneration.

Background: Adipose-derived stem cells (ADSCs) promote lymphangiogenesis, though their integration with vascularized lymph node transfer (VLNT) is not well-explored. Unlike ADSCs, the stromal vascular fraction (SVF) can be obtained intraoperatively without the need for cell culture, making it ideal for incorporation into VLNT in a single-stage surgical procedure. This study evaluates the impacts of combined VLNT and SVF therapy using a rabbit hindlimb model.

Method: New Zealand white rabbits were divided into four groups: control, VLNT only, SVF only, and combined VLNT plus SVF. The VLNT procedure involved transferring a pedicled lymph node flap, while the SVF was harvested and injected into the perinodal tissue. Postoperative assessments included measuring edema volume, performing ICG lymphography, conducting histological analysis, and measuring VEGF-C and LYVE-1 expression.

Results: Initial increases in hindlimb edema volume were noted, but a significant decrease occurred by week 4, particularly in the VLNT group and VLNT plus SVF group compared to the control group. Histological evaluations indicated that the combined treatment group preserved superior structural integrity of the lymph nodes, with a decreased proportion of fibroadipose tissue compared to the VLNT-only group. Elevated VEGF-C expression was observed in the SVF-treated groups, as confirmed by both RT-PCR and ELISA analyses at week 4. Additionally, the combined VLNT plus SVF group showed increased LYVE-1 expression by week 8.

Conclusion: The results suggest that SVF can be effectively integrated with VLNT in a single-stage procedure, enhancing the viability and structural integrity of vascularized lymph nodes. These results highlight the potential of this combined approach as a promising therapeutic strategy for advanced-stage lymphedema, meriting further exploration in clinical trials.

Background: Bone scaffolds are artificial structures used for restoring bone functionality via the reconstruction and repair of bone tissue. Although these scaffolds interact seamlessly with the surrounding tissue, conventional scaffold designs often fail to consider the microstructure of the surrounding bone, leading to reduced mechanical performance. This study proposed an implantation angle optimization approach for bone scaffolds that considers the microstructures around the implant, thus improving the mechanical properties of commonly used scaffolds.

Method: This study proposed a novel method for optimizing the implantation angle of bone scaffolds, thereby enhancing their mechanical performance and integration with the surrounding bone tissue. A finite element model based on the imaging data of the bone scaffold within the skeletal system was constructed. Then, the structural behavior under external load was analyzed to determine the optimal implantation angle by rotating the bone scaffold.

Result: Bone scaffolds with optimized angles show up to 7.53% strain energy difference between the scaffold and native bone, which improves load transfer and supports more natural bone remodeling. These results suggest that this approach enhances scaffold stability and reduces the risk of implant failure.

Conclusion: The results highlight the potential of the proposed approach to optimize the implantation angle considering the bone microstructure, thus significantly enhancing scaffold performance. The combination of these strategies shows significant potential for advancing bone-repair solutions and improving patient outcomes in orthopedic surgeries.

Background: The design of bone biomaterials has shifted from promoting bone differentiation to "immune osteogenic coupling". Macrophages play a key role in immune regulation, with their polarization state critically shaping the bone tissue immune microenvironment. While collagen membranes, as classic guided bone regeneration (GBR) barriers, offer excellent biocompatibility and degradability, they lack inherent bone induction and immune regulation capabilities, limiting their use in complex bone defect repair.

Methods: In this study, we proposed a novel optimization strategy utilizing phase-transited lysozymes (PTL) incorporating strontium (Sr²⁺) into marine collagen membranes (Sr-PTL-MCM) and investigate their osteoimmunomodulatory effect through a series of experiments.

Results: Sr-PTL-MCM were successfully synthesized via the PTL technique and continuously released Sr²⁺ ions over 7 days. Sr-PTL-MCM can effectively induce macrophage polarization from the M0 to M2 phenotype, suppresses the secretion of inflammatory cytokines, thereby enhancing mBMSCs osteogenic differentiation. RNA-sequence analysis reveals that Sr-PTL-MCM promotes M2 polarization via JAK-STAT and MAPK signaling pathways. In vivo experiments confirm its ability to create a favorable bone immune microenvironment, promoting bone growth and regeneration.

Conclusion: In conclusion, incorporating Sr ions into collagen via PTL technique represents a promising approach for developing collagen membranes with immunomodulatory characteristics, thereby providing a novel and effective strategy for bone defect repair.

Background: The ultimate goal of regenerative medicine is to restore damaged tissues to a healthy state in the body. Direct reprogramming, also referred to as transdifferentiation, holds significant therapeutic potential by converting abundant somatic cells, such as fibroblasts, into functionally distinct cell types for tissue regeneration. Despite its potential applications in regenerative medicine, direct reprogramming faces major challenges, including low efficiency and poor In vivo applicability. In this study, we propose a novel therapeutic strategy for osteoporosis based on In vivo direct reprogramming using a stepwise delivery approach that first enhances cellular stemness and subsequently induces osteogenic transdifferentiation. Enhancing stemness in lineage-committed cells facilitates their conversion into other functional cell types.

Method: To investigate the efficiency of direct reprogramming via stepwise delivery, we utilized valproic acid (VPA) and tauroursodeoxycholic acid (TUDCA) as reprogramming and bone-stimulating factors, respectively. VPA increased the expression of stemness genes, including Oct4, Nanog, and Sox2, and subsequent treatment of TUDCA enhanced the expression of osteogenic genes in the mouse fibroblast. Targeted delivery of these factors to fibroblasts surrounding bone tissue, enabling subsequent direct reprogramming into osteoblasts, was achieved using bisphosphonate (BP)-conjugated lipid nanoparticles as carriers.

Results: Our findings demonstrate that sequential induction of cell reprogramming and tissue regeneration through stepwise administration of VPA and TUDCA significantly enhances therapeutic efficacy in a mouse model of osteoporosis compared to their simultaneous administration.

Conclusion: This stepwise bone-targeted drug delivery system presents a promising strategy for osteoporosis treatment via In vivo direct reprogramming.

Background: Enamel regeneration and remineralization are critical for restoring enamel integrity, as natural enamel lacks the ability to regenerate due to the absence of ameloblasts. The increasing prevalence of dental caries and the irreversible nature of enamel damage highlight the need for advanced repair strategies.

Methods: This review examines the latest advancements in enamel regeneration and remineralization, focusing on biomaterials, nanotechnology-based approaches, and bioengineering strategies. Google Scholar, Scopus (Elsevier), and PubMed databases were used for the selection of literature. The search included key terms such as "enamel regeneration," "biomimetic enamel repair," "stem cell-based enamel regeneration," "nanotechnology in enamel repair," "hydroxyapatite enamel remineralization," and "biomaterials for enamel remineralization."

Results: Various strategies have been explored for enamel remineralization, including self-assembling peptides, dendrimers, hydrogels, and electrospun mats, each demonstrating varying success in laboratory and preclinical studies. While casein-phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) combined with fluoride remains a widely used clinical remineralization agent, integrating CPP-ACP with nanotechnology is an emerging area requiring further research. Enamel bioengineering approaches utilizing stem/progenitor cells offer potential, though challenges remain in achieving clinical translation.

Conclusion: Despite advancements, replicating the hierarchical structure and mechanical properties of natural enamel remains challenging. Nanotechnology-driven approaches, bioengineered scaffolds, and interdisciplinary collaboration hold promise for optimizing enamel regeneration techniques. Further research is necessary to enhance clinical applicability and develop scalable, effective treatments for enamel restoration.

Background: Wound healing remains a significant challenge in healthcare, particularly for complex and chronic wounds where conventional treatments often fail to provide effective solutions. Recent advances in nanofiber technology have opened new avenues for wound management by offering biomimetic structures that support tissue regeneration. Due to their high surface area-to-volume ratio and porosity, nanofibers closely resemble the extracellular matrix, facilitating an optimal environment for cell adhesion, proliferation, and differentiation.

Methods: This review examines the role of nanofiber-based wound dressings, highlighting their unique advantages in drug delivery, moisture retention, and antimicrobial protection. Additionally, emerging trends such as smart wound dressings responsive to environmental stimuli and multifunctional nanofiber systems are discussed.

Results and conclusion: Nanofiber technology has demonstrated significant potential in enhancing wound healing outcomes by providing an advanced platform for therapeutic delivery and tissue regeneration. Furthermore, the integration of nanofibers with artificial intelligence and biotechnology offers promising directions for future research. As these innovations continue to evolve, nanofiber-based wound dressings may revolutionize wound care by enabling more personalized and effective treatment strategies.

Background: Recently, regenerative medicine based on cell-based therapies has emerged as a therapeutic possibility for the management of osteoarthritis (OA). Stromal vascular fraction (SVF) is a cellular mixture obtained from lipoaspirate processed through either mechanical or enzymatic separation. SVF has been applied in several countries to treat OA patients without robust supporting evidence or comprehensive evaluation.

Methods: This review purposes to summarize clinical evidence regarding SVF as a therapeutic for OA and to introduce the author's perspective. Eleven studies were found suitable for this review; out of these, seven were randomized clinical trials and four were cohort studies.

Results: A review of controlled studies suggests that SVF may offer better symptomatic relief than placebo or hyaluronic acid in the long term, and the effect of SVF is comparable to that of bone marrow aspirate concentrates.

Conclusion: Prospective studies with improved control over the cell isolation method, dosage, and patient selection are necessary to provide convincing evidence of the benefits of SVF in treating OA.