Preparation and assessment of an optimized multichannel acellular nerve allograft for peripheral nerve regeneration.

Peripheral nerve regeneration after injury is still a clinical problem. The application of autologous nerve grafting, the gold standard treatment, is greatly restricted. Acellular nerve allografts (ANAs) are considered promising alternatives, but they are difficult to achieve satisfactory therapeutic outcomes, which may be attributed to their compact inherent ultrastructure and substantial loss of extracellular matrix (ECM) components. Regarding these deficiencies, this study developed an optimized multichannel ANA by a modified decellularization method. These innovative ANAs were demonstrated to retain more ECM bioactive molecules and regenerative factors, with effective elimination of cellular antigens. The presence of microchannels with larger pore size allowed ANAs to gain higher porosity and better swelling performance, which improves their internal ultrastructure. Their mechanical properties were more similar to those of native nerves. Moreover, the optimized ANAs exhibited good biocompatibility and possessed significant advantages in supporting the proliferation and migration of Schwann cells in vitro. The in vivo results further confirmed their superior capacity to promote axon regrowth and myelination as well as restore innervation of target muscles, leading to better functional recovery than the conventional ANAs. Overall, this study demonstrates that the optimized multichannel ANAs have great potential for clinical application and offer new insight into the further improvement of ANAs.

Sequential expression of miR-221-3p and miR-338-3p in Schwann cells as a therapeutic strategy to promote nerve regeneration and functional recovery.

The functional properties of endogenous Schwann cells (SCs) during nerve repair are dynamic. Optimizing the functional properties of SCs at different stages of nerve repair may have therapeutic benefit in improving the repair of damaged nerves. Previous studies showed that miR-221-3p promotes the proliferation and migration of SCs, and miR-338-3p promotes the myelination of SCs. In this study, we established rat models of sciatic nerve injury by bridging the transected sciatic nerve with a silicone tube. We injected a miR-221 lentiviral vector system together with a doxycycline-inducible Tet-On miR-338 lentiviral vector system into the cavity of nerve conduits of nerve stumps to sequentially regulate the biological function of endogenous SCs at different stages of nerve regeneration. We found that the biological function of SCs was sequentially regulated, the diameter and density of myelinated axons were increased, the expression levels of NF200 and myelin basic protein were increased, and the function of injured peripheral nerve was improved using this system. miRNA Target Prediction Database prediction, Nanopore whole transcriptome sequencing, quantitative PCR, and dual luciferase reporter gene assay results predicted and verified Cdkn1b and Nrp1 as target genes of miR-221-3p and miR-338-3p, respectively, and their regulatory effects on SCs were confirmed in vitro. In conclusion, here we established a new method to enhance nerve regeneration through sequential regulation of biological functions of endogenous SCs, which establishes a new concept and model for the treatment of peripheral nerve injury. The findings from this study will provide direct guiding significance for clinical treatment of sciatic nerve injury.

Gingival mesenchymal stem cell-derived exosomes are immunosuppressive in preventing collagen-induced arthritis.

Due to the unsatisfied effects of clinical drugs used in rheumatoid arthritis (RA), investigators shifted their focus on the biotherapy. Although human gingival mesenchymal stem cells (GMSC) have the potential to be used in treating RA, GMSC-based therapy has some inevitable side effects such as immunogenicity and tumorigenicity. As one of the most important paracrine mediators, GMSC-derived exosomes (GMSC-Exo) exhibit therapeutic effects via immunomodulation in a variety of disease models, bypassing potential shortcomings of the direct use of MSCs. Furthermore, exosomes are not sensitive to freezing and thawing, and can be readily available for use. GMSC-Exo has been reported to promote tissue regeneration and wound healing, but have not been reported to be effective against autoimmune diseases. We herein compare the immunomodulatory functions of GMSC-Exo and GMSC in collagen-induced arthritis (CIA) model and in vitro CD4+ T-cell co-culture model. The results show that GMSC-Exo has the same or stronger effects compared with GMSC in inhibiting IL-17A and promoting IL-10, reducing incidences and bone erosion of arthritis, via inhibiting IL-17RA-Act1-TRAF6-NF-κB signal pathway. Our results suggest that GMSC-Exo has many advantages in treating CIA, and may offer a promising new cell-free therapy strategy for RA and other autoimmune diseases.

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.

CD300a and CD300f molecules regulate the function of leukocytes.

The CD300 molecule family is a type I transmembrane glycoprotein expressed on cell membrane of human and other mammals, and of its eight members, only CD300a and CD300f are classified as inhibitory receptors. CD300a and CD300f play an important role in regulating the function of leukocytes, such as activation, proliferation, differentiation, migration and immunity function. They are considered as potential targets for studying the development and progression of inflammation, infection and other diseases. Here, we review the expression and regulatory mechanisms of CD300a and CD300f on leukocytes, as well as their effects on relevant diseases.

Effects of microRNA-338 Transfection into Sciatic Nerve on Rats with Experimental Autoimmune Neuritis.

Nerve demyelination or axonal lesions are characteristic of experimental autoimmune neuritis (EAN). Previous studies have demonstrated that microRNA-338 can regulate the differentiation and maturation of oligodendrocytes and Schwann cells and promote injured peripheral nerves in rats. In this study, we used microRNA-338 coded lentivirus vector (miR-338-LV) in a Lewis rat EAN model, in with the conjunction P0 peptide 180-199 which was injected into the footpads of animals to induce immunization. The clinical scores of miR-338-LV and intravenous immunoglobulin (IVIg) (positive drug) groups were significantly superior to those of untreated group at disease peak and disease plateau (p < 0.05). The nerve conduction velocity and the compound nerve action potential amplitude of miR-338-LV and IVIg groups increased significantly compared to those of the untreated group at disease peak (p < 0.01). At disease peak, myelin swelling, cavity formation, and lamellae separation showed improvement in miR-338-LV and IVIg groups compared to untreated group. S100 and NF200 expression in miR-338-LV and IVIg groups increased compared to that in untreated group. Iba1 and S100 co-expression in Schwann cells in miR-338-LV and IVIg groups decreased compared to that in untreated group, which was indicative of the reduced conversion of Schwann cells into inflammatory cells. Overall, miR-338-LV in sciatic nerves might improve neuromuscular function in EAN by inhibiting the conversion of Schwann cells into inflammatory cells.