Objective:To study the repair impact of recombinant human collagen Ⅲ(rhCol Ⅲ)hydrogel with sus-tained cell-free fat extract(CEFFE)release on spinal cord injury(SCI).Methods:The rhCol Ⅲ hydrogel was com-bined with CEFFE to create a composite scaffold capable of releasing CEFFE.Rats with SCI hemicut models were divid-ed into three groups:SCI,rhCol Ⅲ,and rhCol Ⅲ/CEFFE.Results:The rhCol Ⅲ/CEFFE hydrogel features a three-dimensional(3D)porous structure and suitable elasticity,enabling continuous CEFFE release.This group demonstra-ted notable motor function improvement and more complete spinal cord tissue continuity compared to other greups.The enzyme-linked immunosorbent assay(ELISA),Luxol fast blue staining(LFB),and immunofluorescence results dem-onstrated that RhCol Ⅲ/CEFFE hydrogel inhibits inflammatory factors,encourages microglia M2 transformation,reduces glial scar formation,and promotes neuronal differentiation,axonal regeneration,and myelin sheath formation.Conclusion:The rhCol Ⅲ/CEFFE hydrogel reshapes the inhibitory microenvironment,supports nerve regeneration and neural network formation,and aids in neural function recovery.

Objective:To study the repair impact of recombinant human collagen Ⅲ(rhCol Ⅲ)hydrogel with sus-tained cell-free fat extract(CEFFE)release on spinal cord injury(SCI).Methods:The rhCol Ⅲ hydrogel was com-bined with CEFFE to create a composite scaffold capable of releasing CEFFE.Rats with SCI hemicut models were divid-ed into three groups:SCI,rhCol Ⅲ,and rhCol Ⅲ/CEFFE.Results:The rhCol Ⅲ/CEFFE hydrogel features a three-dimensional(3D)porous structure and suitable elasticity,enabling continuous CEFFE release.This group demonstra-ted notable motor function improvement and more complete spinal cord tissue continuity compared to other greups.The enzyme-linked immunosorbent assay(ELISA),Luxol fast blue staining(LFB),and immunofluorescence results dem-onstrated that RhCol Ⅲ/CEFFE hydrogel inhibits inflammatory factors,encourages microglia M2 transformation,reduces glial scar formation,and promotes neuronal differentiation,axonal regeneration,and myelin sheath formation.Conclusion:The rhCol Ⅲ/CEFFE hydrogel reshapes the inhibitory microenvironment,supports nerve regeneration and neural network formation,and aids in neural function recovery.

Objective To investigate the feasibility of human amniotic mesenchymal stem cells (hAMSCs) transplantation to improve the survival of ischemic ultra-long random skin flap vascularization,so as to promote the survival of skin flap.Methods The hAMSCs were isolated from human amnion,cultured in vitro,and identified by immunocytochemistry.The phenotype of hAMSCs was analyzed by flow cytometry.CellTrackerTM-CM-Dil was used to label before hAMSCs transplantation into skin flap.Twenty SD adult rats were selected and the 2 cm × 8 cm ischemic ultra-long random skin flap models were constructed in the left and right sides of the rat back.The pedicles of flaps were on the lliac crest level.The flaps were divided into left group (injection with 0.5 ml LG-DMEM) and right group (0.5 ml 1 × 106/ml hAMSCs) after the flap was lifted.The survival rate of flap was observed 7 d after surgery.The blood perfusion values,namely blood perfusion unit at pedicle and in the middle,were monitored by laser Doppler flow monitor at the immediate time,24 h,48 h,4 d and 7 d of the skin flap after surgery.The capillary density of the skin flap was observed through histological observation of the tissue (0.5 cm from adult and necrotic junction).The distribution and survival rate of CM-Dil labeled hAMSCs were observed by fluorescent microscope.Results In term of survival rate of the flap,left group was (50.6 ± 2.2) ％,and right group was (70.9 ± 2.1) ％.The survival rate of the flap in right group was greater than that of left group (P ＜ 0.05).Blood perfusion unit detected in the pedicle of left group at days 4 and 7 after surgery was higher than that of the right group (P ＜ 0.05).Blood perfusion unit in middle of flap of left group at 24 h,48 h,4 d and 7 d were lower than that of right group (P ＜ 0.05).The flap capillary density at 7 d after surgery were (8.8 ± 1.2)/mm2 in left group and (23.5 ± 1.6)/mm2 in right group (P ＜ 0.05).The tissue of flap was made frozen section,and the fluorescence microscope showed there were CM-Dil labeled hAMSCs in skip flap in right group,which could manifest the survival and distribution of hAMSCs in skip flap.Conclusion The application of hAMSCs in the middle and distal parts of ultralong random skin flap can significantly improve the survival rate of skin flap,and increase the density of microvascular reconstruction in the flap.