Enhancing neuroinduction activity of PLCL-based nerve conduits through native epineurium integration.

Autologous nerve grafts have been considered the gold standard for peripheral nerve grafts. However, due to drawbacks such as functional loss in the donor area and a shortage of donor sources, nerve conduits are increasingly being considered as an alternative approach. Polymer materials have been widely studied as nerve repair materials due to their excellent processing performance. However, their limited biocompatibility has restricted further clinical applications. The epineurium is a natural extra-neural wrapping structure. After undergoing decellularization, the epineurium not only reduces immune rejection but also retains certain bioactive components. In this study, decellularized epineurium (DEP) derived from the sciatic nerve of mammals was prepared, and a bilayer nerve conduit was created by electrospinning a poly (l-lactide-co-ε-caprolactone) (PLCL) membrane layer onto the outer surface of the DEP. Components of the DEP were examined; the physical properties and biosafety of the bilayer nerve conduit were evaluated; and the functionality of the nerve conduit was evaluated in rats. The results demonstrate that the developed bilayer nerve conduit exhibits excellent biocompatibility and mechanical properties. Furthermore, this bilayer nerve conduit shows significantly superior therapeutic effects for sciatic nerve defects in rats compared to the pure PLCL nerve conduit. In conclusion, this research provides a novel strategy for the design of nerve regeneration materials and holds promising potential for further clinical translation.

Malate-Based Biodegradable Scaffolds Activate Cellular Energetic Metabolism for Accelerated Wound Healing.

The latest advancements in cellular bioenergetics have revealed the potential of transferring chemical energy to biological energy for therapeutic applications. Despite efforts, a three-dimensional (3D) scaffold that can induce long-term bioenergetic effects and facilitate tissue regeneration remains a big challenge. Herein, the cellular energetic metabolism promotion ability of l-malate, an important intermediate of the tricarboxylic acid (TCA) cycle, was proved, and a series of bioenergetic porous scaffolds were fabricated by synthesizing poly(diol l-malate) (PDoM) prepolymers via a facial one-pot polycondensation of l-malic acid and aliphatic diols, followed by scaffold fabrication and thermal-cross-linking. The degradation products of the developed PDoM scaffolds can regulate the metabolic microenvironment by entering mitochondria and participating in the TCA cycle to elevate intracellular adenosine triphosphate (ATP) levels, thus promoting the cellular biosynthesis, including the production of collagen type I (Col1a1), fibronectin 1 (Fn1), and actin alpha 2 (Acta2/α-Sma). The porous PDoM scaffold was demonstrated to support the growth of the cocultured mesenchymal stem cells (MSCs) and promote their secretion of bioactive molecules [such as vascular endothelial growth factor (VEGF), transforming growth factor-ß1 (TGF-ß1), and basic fibroblast growth factor (bFGF)], and this stem cells-laden scaffold architecture was proved to accelerate wound healing in a critical full-thickness skin defect model on rats.

Nerve ECM and PLA-PCL based electrospun bilayer nerve conduit for nerve regeneration.

Introduction: The porcine nerve-derived extracellular matrix (ECM) fabricated as films has good performance in peripheral nerve regeneration. However, when constructed as conduits to bridge nerve defects, ECM lacks sufficient mechanical strength. Methods: In this study, a novel electrospun bilayer-structured nerve conduit (BNC) with outer poly (L-lactic acid-co-ε-caprolactone) (PLA-PCL) and inner ECM was fabricated for nerve regeneration. The composition, structure, and mechanical strength of BNC were characterized. Then BNC biosafety was evaluated by cytotoxicity, subcutaneous implantation, and cell affinity tests. Furthermore, BNC was used to bridge 10-mm rat sciatic nerve defect, and nerve functional recovery was assessed by walking track, electrophysiology, and histomorphology analyses. Results: Our results demonstrate that BNC has a network of nanofibers and retains some bioactive molecules, including collagen I, collagen IV, laminin, fibronectin, glycosaminoglycans, nerve growth factor, and brain-derived neurotrophic factor. Biomechanical analysis proves that PLA-PCL improves the BNC mechanical properties, compared with single ECM conduit (ENC). The functional evaluation of in vivo results indicated that BNC is more effective in nerve regeneration than PLA-PCL conduit or ENC. Discussion: In conclusion, BNC not only retains the good biocompatibility and bioactivity of ECM, but also obtains the appropriate mechanical strength from PLA-PCL, which has great potential for clinical repair of nerve defects.

Biobased Chicken Eggshell Powder for Efficient Delivery of Low-Dose Silver Nanoparticles (AgNPs) to Enhance Their Antimicrobial Activities against Foodborne Pathogens and Biofilms.

Despite the current sanitation practices to decontaminate food-contact surfaces, persistent biofilms still pose significant threats to human health by inducing cross-contamination. This study aims to enhance the antimicrobial activity of low-dose silver nanoparticles (AgNPs) against foodborne pathogens and their biofilms through the development of a biobased delivery carrier for metallic nanoparticles. In this study, chicken eggshell powder (EP) was used as a biocompatible delivery carrier, and it possesses a strong ability to encapsulate green-synthesized AgNPs with an encapsulation efficiency of 80.18%. The EP carriers stabilized AgNPs in an organic-rich environment and prevented the aggregation of nanoparticles. The results of antimicrobial test demonstrate that EP significantly enhanced the antimicrobial efficacy of low-dose AgNPs (2 µg/mL), enabling 5-log reductions of planktonic Escherichia coli and Listeria innocua within 25 min and 60 min treatments, respectively, even in the presence of high organic content (chemical oxygen demand, COD = 1000 mg/L). Due to the high affinity of EP to bind biofilms, the encapsulated low-dose AgNPs can inactivate approximately 2-log CFU/cm2 of biofilms within a 2-h treatment. The proposed AgNPs@EP composite with a low silver concentration (2 µg/mL) can effectively inactivate and remove biofilms from food-contact surfaces in which such a low concentration of AgNPs is unlikely to induce negative impacts on human health and environment. Therefore, this antimicrobial AgNPs@EP composite can potentially be used as a biobased sanitizer for food-contact surfaces in a food manufacturing plant.

Poly (ɛ-Caprolactone-co-l,l-Lactide) Vascular External Sheath Carrying Prednisone for Improving Patency Rate of the Vein Graft.

Coronary artery bypass graft (CABG) surgery is an impactful treatment for coronary heart disease. Intimal hyperplasia is the central reason for the restenosis of vein grafts (VGs) after CABG. The introduction of external vascular sheaths around VGs can effectively inhibit intimal hyperplasia and ensure the patency of VGs. In this study, the well-known biodegradable copolymer poly (ɛ-caprolactone-co-l,l-lactide) (PLCL) was electrospun into high porosity external sheaths. The prednisone loaded in the PLCL sheath was slowly released during the degradation process of PLCL. Under the combined effects of sheath and prednisone, intimal hyperplasia was inhibited. For the cell experiments, all sheaths show low cytotoxicity to L929 cells at different concentrations at different time intervals. The ultrasonography and histological results showed prominent dilation and intimal hyperplasia of VG without sheath after 2 months of surgery. But there was no dilation in PLCL and PLCLPrednisone groups. Of note, the prednisone-loaded sheath group exhibited efficacy in inhibiting intimal hyperplasia and ensured graft patency. Impact statement To inhibit intimal hyperplasia after coronary artery bypass graft, the use of external vascular sheaths can prevent vein graft (VG) dilatation, then reduce turbulent blood flow shear stress to vessel wall, and lower the stimulation of shear stress to smooth muscle cells (SMCs), so as to prevent the proliferation and migration of vascular SMC. We provide a biodegradable sheath electrospun by poly (ɛ-caprolactone-co-l,l-lactide) (PLCL) loading prednisone and utilize it around VG in animal models. Vascular ultrasound examinations show strong evidence of vascular patency. The histological alterations of VGs in PLCLPrednisone group gave a narrower intima layer owing to the inhibition effect of prednisone.

Fabrication and evaluation of an optimized xenogenic decellularized costal cartilage graft: preclinical studies of a novel biocompatible prosthesis for rhinoplasty.

On account of the poor biocompatibility of synthetic prosthesis, millions of rhinoplasty recipients have been forced to choose autologous costal cartilage as grafts, which suffer from limited availability, morbidity at the donor site and prolonged operation time. Here, as a promising alternative to autologous costal cartilage, we developed a novel xenogeneic costal cartilage and explored its feasibility as a rhinoplasty graft for the first time. Adopting an improved decellularization protocol, in which the ionic detergent was substituted by trypsin, the resulting decellularized graft was confirmed to preserve more structural components and better mechanics, and eliminate cellular components effectively. The in vitro and in vivo compatibility experiments demonstrated that the decellularized graft showed excellent biocompatibility and biosecurity. Additionally, the functionality assessment of rhinoplasty was performed in a rabbit model, and the condition of grafts after implantation was comprehensively evaluated. The optimized graft exhibited better capacity to reduce the degradation rate and maintain the morphology, in comparison to the decellularized costal cartilage prepared by conventional protocol. These findings indicate that this optimized graft derived from decellularized xenogeneic costal cartilage provides a new prospective for future investigations of rhinoplasty prosthesis and has great potential for clinical application.

Decellularized tendon matrix membranes prevent post-surgical tendon adhesion and promote functional repair.

Adhesion often occurs after tendon injury, and results in sliding disorder and movement limitation with no ideal solution for it in clinic. In this study, an anti-adhesion membrane, i.e., decellularized tendon matrix (DTM) for tendon is successfully prepared by an optimized tendon decellularization method from homologous extracellular matrix. Microsection technology has been used to optimize the method of decellularization in order to better preserve the bioactive components in tissues and reduce the chemical reagent residues on the premise of effective decellularization with relatively shorter time and less reagents for decellularization. The physic-chemical properties and biological functions of DTM are evaluated, and high-throughput and high-precision tandem mass tags (TMT) labeling proteomics technology is used to analyze protein components of DTM, which may provide the scientific support for application of the innovative product. In vitro biosafety tests show that DTM not only is non-toxic but also promote cell proliferation. Subcutaneous implantation test confirms that DTM is completely degraded after 12 weeks and there is no obvious inflammatory reaction. The results of Achilles tendon repair in rabbits show that DTM can not only prevent tendon adhesion but also improve the quality of tendon repair, which demonstrates its tremendous application potential. STATEMENT OF SIGNIFICANCE: There is no ideal solution for adhesion after tendon injury. In this study, a dense tendon anti-adhesion membrane (DTM) was successfully prepared from homologous extracellular matrix (ECM). This DTM could effectively retain bioactive ingredients, and prevent adhesion as well as improve the quality of tendon repair in vivo. An optimized decellularization method was used which could effectively decellularize tendon in a short time, better preserve bioactive components, and reduce reagent residues. For the first time, high-throughput and high-precision tandem mass tags (TMT) labeling proteomics technology was used to qualitatively and quantitatively analyze the protein composition of fresh tendon, acellular tendon and DTM, which provided not only scientific support for the application of DTM, but also comprehensive and accurate data support for related research of bovine tendons and decellularization.

Sterilization and disinfection methods for decellularized matrix materials: Review, consideration and proposal.

Sterilization is the process of killing all microorganisms, while disinfection is the process of killing or removing all kinds of pathogenic microorganisms except bacterial spores. Biomaterials involved in cell experiments, animal experiments, and clinical applications need to be in the aseptic state, but their physical and chemical properties as well as biological activities can be affected by sterilization or disinfection. Decellularized matrix (dECM) is the low immunogenicity material obtained by removing cells from tissues, which retains many inherent components in tissues such as proteins and proteoglycans. But there are few studies concerning the effects of sterilization or disinfection on dECM, and the systematic introduction of sterilization or disinfection for dECM is even less. Therefore, this review systematically introduces and analyzes the mechanism, advantages, disadvantages, and applications of various sterilization and disinfection methods, discusses the factors influencing the selection of sterilization and disinfection methods, summarizes the sterilization and disinfection methods for various common dECM, and finally proposes a graphical route for selecting an appropriate sterilization or disinfection method for dECM and a technical route for validating the selected method, so as to provide the reference and basis for choosing more appropriate sterilization or disinfection methods of various dECM.

Preparation and evaluation of acellular sheep periostea for guided bone regeneration.

The objective of this study was to fabricate an acellular sheep periosteum and explore its potential application in guided bone regeneration. Sheep periosteum was collected and decellularized by a modified decellularization protocol. The effectiveness of cell removal was proved by hematoxylin and eosin and 4',6-diamidino-2-phenylindole staining, DNA quantitative test, and agarose gel electrophoresis. After decellularization, its microstructure was found to become more porous while the integrality of collagen fibers remained undamaged, and the contents of collagen and glycosaminoglycan were not decreased significantly. Biomechanical analysis showed that the elastic modulus was significantly declined, while the yield stress was not affected, probably due to the collagen integrality. In vitro study of CCK-8 assay demonstrated that the acellular periosteum not only had no toxic effect to the MC3T3-E1 cells, but benefited the cell proliferation to some degree. In vivo experiment of guided bone regeneration was performed using a rabbit cranial model. Micro-CT and histological results revealed that the acellular periosteum not only effectively prevented the ingrowth of fibrous connective tissues, but also potentially facilitated bone regeneration. In conclusion, acellular sheep periostea, with wider sources, less costs, and more convenient fabrication process, would have great potential in the employment for guided bone regeneration.

In vitro and in vivo biocompatibility study on acellular sheep periosteum for guided bone regeneration.

This study addresses the fabrication of an extracellular matrix material of the acellular sheep periosteum and the systematic evaluation of its biocompatibility to explore its potential application in guided bone regeneration. Sheep periosteum was harvested and decellularized by a combined decellularization protocol. The effectiveness of cell removal was proved and residual α-Gal antigen was also quantitatively detected. Then, mouse MC3T3-E1 cells were seeded onto the acellular periosteum. A scanning electron microscope (SEM) was used to record the whole process of cell adhesion. The CCK-8 assay suggested that the acellular periosteum not only had zero toxic effect on pre-osteoblasts, but played a positive role in cell proliferation. We also tested whether the acellular periosteum possesses favorable osteogenesis induction activity using an alkaline phosphatase (ALP) assay and a quantitative real-time PCR (Col I, Runx2, OCN) assay. An in vivo study of a subcutaneous implantation test using Sprague Dawley (SD) rats was performed to detect the changes in IL-2, IFN-γ and IL-4 in serum and elucidate the host's local response to acellular periosteum through hematoxylin and eosin (HE) and immunohistochemical staining. The results show that acellular sheep periosteum did not elicit a severe immunogenic response via the Th1 pathway, unlike fresh sheep periosteum. In conclusion, acellular sheep periosteum possesses favorable biocompatibility to be employed for guided bone regeneration.