Human nail bed‐derived decellularized scaffold regulates mesenchymal stem cells for nail plate regeneration

ECM-derived biomaterials for regulating tissue multicellularity and maturation

Recent breakthroughs in developing human-relevant organotypic models led to the building of highly resemblant tissue constructs that hold immense potential for transplantation, drug screening, and disease modeling. Despite the progress in fine-tuning stem cell multilineage differentiation in highly controlled spatiotemporal conditions and hosting microenvironments, 3D models still experience naive and incomplete morphogenesis. In particular, existing systems and induction protocols fail to maintain stem cell long-term potency, induce high tissue-level multicellularity, or drive the maturity of stem cell-derived 3D models to levels seen in their in vivo counterparts. In this review, we highlight the use of extracellular matrix (ECM)-derived biomaterials in providing stem cell niche-mimicking microenvironment capable of preserving stem cell long-term potency and inducing spatial and region-specific differentiation. We also examine the maturation of different 3D models, including organoids, encapsulated in ECM biomaterials and provide looking-forward perspectives on employing ECM biomaterials in building more innovative, transplantable, and functional organs.

Matrisomal components involved in regenerative wound healing in axolotl and Acomys: implications for biomaterial development

Achieving regeneration in humans has been a long-standing goal of many researchers. Whereas amphibians like the axolotl (Ambystoma mexicanum) are capable of regenerating whole organs and even limbs, most mammals heal their wounds via fibrotic scarring. Recently, the African spiny mouse (Acomys sp.) has been shown to be injury resistant and capable of regenerating several tissue types. A major focal point of research with Acomys has been the identification of drivers of regeneration. In this search, the matrisome components related to the extracellular matrix (ECM) are often overlooked. In this review, we compare Acomys and axolotl skin wound healing and blastema-mediated regeneration by examining their wound healing responses and comparing the expression pattern of matrisome genes, including glycosaminoglycan (GAG) related genes. The goal of this review is to identify matrisome genes that are upregulated during regeneration and could be potential candidates for inclusion in pro-regenerative biomaterials. Research papers describing transcriptomic or proteomic coverage of either skin regeneration or blastema formation in Acomys and axolotl were selected. Matrisome and GAG related genes were extracted from each dataset and the resulting lists of genes were compared. In our analysis, we found several genes that were consistently upregulated, suggesting possible involvement in regenerative processes. Most of the components have been implicated in regulation of cell behavior, extracellular matrix remodeling and wound healing. Incorporation of such pro-regenerative factors into biomaterials may help to shift pro-fibrotic processes to regenerative responses in treated wounds.

Biomimetic hydrogel derived from decellularized dermal matrix facilitates skin wounds healing

Cutaneous wound healing affecting millions of people worldwide represents an unsolvable clinical issue that is frequently challenged by scar formation with dramatical pain, impaired mobility and disfigurement. Herein, we prepared a kind of light-sensitive decellularized dermal extracellular matrix-derived hydrogel with fast gelling performance, biomimetic porous microstructure and abundant bioactive functions. On account of its excellent cell biocompatibility, this ECM-derived hydrogel could induce a marked cellular infiltration and enhance the tube formation of HUVECs. In vivo experiments based upon excisional wound splinting model showed that the hydrogel prominently imparted skin wound healing, as evidenced by notably increased skin appendages and well-organized collagen expression, coupled with significantly enhanced angiogenesis. Moreover, the skin regeneration mediated by this bioactive hydrogel was promoted by an accelerated M1-to-M2 macrophage phenotype transition. Consequently, the decellularized dermal matrix-derived bioactive hydrogel orchestrates the entire skin healing microenvironment to promote wound healing and will be of high value in treatment of cutaneous wound healing. As such, this biomimetic ddECMMA hydrogel provides a promising versatile opinion for the clinical translation.

Perfusion decellularization for vascularized composite allotransplantation

Vascularized composite allotransplantation is becoming the emerging standard for reconstructive surgery treatment for patients with limb trauma and facial injuries involving soft tissue loss. Due to the complex immunogenicity of composite grafts, patients who undergo vascularized composite allotransplantation are reliant on lifelong immunosuppressive therapy. Decellularization of donor grafts to create an extracellular matrix bio-scaffold provides an immunomodulatory graft that preserves the structural and bioactive function of the extracellular matrix. Retention of extracellular matrix proteins, growth factors, and signaling cascades allow for cell adhesion, migration, proliferation, and tissue regeneration. Perfusion decellularization of detergents through the graft vasculature allows for increased regent access to all tissue layers, and removal of cellular debris through the venous system. Grafts can subsequently be repopulated with appropriate cells through the vasculature to facilitate tissue regeneration. The present work reviews methods of decellularization, process parameters, evaluation of adequate cellular and nuclear removal, successful applications of perfusion decellularization for use in vascularized composite allotransplantation, and current limitations.

Human nail bed extracellular matrix facilitates bone regeneration via macrophage polarization mediated by the JAK2/STAT3 pathway

Critical-sized bone defects caused by trauma, tumor resection or serious infection represent one of the most challenging problems faced by orthopedic surgeons. However, the construction of bone grafts with good osteointegration and osteoinductivity is a clinical challenge. It has been elaborated that the nail bed tissue is an essential element for digit tip regeneration, suggesting that the nail bed may serve as a new material to manipulate bone regeneration. Herein, it was found that human nail bed extracellular matrix derived from amputated patients stimulates macrophage polarization toward a pro-healing phenotype and the expression of BMP2, to facilitate the osteogenic differentiation of bone marrow stromal cells (BMSCs) in vitro. The in vivo osteogenic capacity of decellularized nail bed scaffolds was then confirmed using a rat model of critical-sized calvarial defects. The in-depth analysis of immune responses to implanted scaffolds revealed that macrophage polarization toward the pro-regenerative M2 phenotype directs osteogenesis, as confirmed by macrophage depletion. A combination of proteomics analysis and RNA interference verified that the JAK2/STAT3 pathway is the positive regulator of macrophage polarization initiated by the decellularized nail bed during the promoted osteogenesis process. Thus, the decellularized human nail bed scaffold developed in this work is a promising biomaterial for bone regeneration.

Nail matrix regenerative engineering: in vitro evaluation of poly(lactide-co-glycolide)/gelatin fibrous substrates

Acute traumatic nail injury treatment repair procedures are commonly conducted in emergency departments and primary care offices. Current repair methods use nail splints that are inserted within the nail root to prevent the fusion of the proximal nail fold and the matrix tissue. Splints provide a protective barrier overlying the nail bed soft tissue during recovery periods, but uncertain prognoses (i.e., aesthetic and functional disadvantages) reveal a need for improved nail repair techniques. Nail splints are not specifically designed for nail organ restoration via biological mechanisms, thus, a clinical application that utilizes regenerative engineering techniques can prove useful in improving the nail injury prognoses. Using the coaxial electrospinning method, hybrid poly(lactide-co-glycolide) (PLGA) (85:15) and gelatin fibrous scaffolds (Hybrid_1: PLGA shell, gelatin core and Hybrid₂ : gelatin shell, PLGA core) with average fiber diameters of 540 ± 118 and 2,215 ± 1,135 nm, respectively, were produced and successful encapsulation of core fibers was observed. Furthermore, nail stem cells expressing stem cell characteristic markers CD90, CD29, and Lgr6 showed preferred attachment to Hybrid₂ scaffolds after 24 hr. Overall, an in vitro regenerative engineered nail matrix may aid to improve the cosmetic appearance and function of injured nail organs post-traumatic injury.