Allotransplantation of adult spinal cord tissues after complete transected spinal cord injury: long-term survival and functional recovery in canines

Spinal cord injury(SCI), especially complete transected SCI, leads to loss of cells and extracellular matrix and functional impairments. In a previous study, we transplanted adult spinal cord tissues(aSCTs) to replace lost tissues and facilitate recovery in a rat SCI model. However, rodents display considerable differences from human patients in the scale, anatomy and functions of spinal cord systems, and responses after injury. Thus, use of a large animal SCI model is required to examine the repair efficiency of potential therapeutic approaches. In this study, we transplanted allogenic aSCTs from adult dogs to the lesion area of canines after complete transection of the thoracic spinal cord, and investigated the long-term cell survival and functional recovery. To enhance repair efficiency, a growth factor cocktail was added during aSCT transplantation, providing a favorable microenvironment. The results showed that transplantation of a SCTs, in particular with the addition of growth factors, significantly improves locomotor function restoration and increases the number of neurofilament-, microtubule-associated protein2-, 5-hydroxytryptamine-, choline acetyltransferase-and tyrosine hydroxylase-positive neurons in the lesion area at 6 months post-surgery. In addition, we demonstrated that donor neurons in a SCTs can survive for a long period after transplantation. This study showed for the first time that transplanting aSCTs combined with growth factor supplementation facilitates reconstruction of injured spinal cords, and consequently promotes long lasting motor function recovery in a large animal complete transected SCI model, and therefore could be considered as a possible therapeutic strategy in humans.

A partition-type tubular scaffold loaded with PDGF-releasing microspheres for spinal cord repair facilitates the directional migration and growth of cells

The best tissue-engineered spinal cord grafts not only match the structural characteristics of the spinal cord but also allow the seed cells to grow and function in situ.Platelet-derived growth factor（PDGF） has been shown to promote the migration of bone marrow stromal cells;however,cytokines need to be released at a steady rate to maintain a stable concentration in vivo.Therefore,new methods are needed to maintain an optimal concentration of cytokines over an extended period of time to effectively promote seed cell localization,proliferation and differentiation.In the present study,a partition-type tubular scaffold matching the anatomical features of the thoracic 8–10 spinal cord of the rat was fabricated using chitosan and then subsequently loaded with chitosan-encapsulated PDGF-BB microspheres（PDGF-MSs）.The PDGF-MS-containing scaffold was then examined in vitro for sustained-release capacity,biocompatibility,and its effect on neural progenitor cells differentiated in vitro from multilineage-differentiating stress-enduring cells（MUSE-NPCs）.We found that pre-freezing for 2 hours at-20°C significantly increased the yield of partition-type tubular scaffolds,and 30 μL of 25% glutaraldehyde ensured optimal crosslinking of PDGF-MSs.The resulting PDGF-MSs cumulatively released 52% of the PDGF-BB at 4 weeks in vitro without burst release.The PDGF-MS-containing tubular scaffold showed suitable biocompatibility towards MUSE-NPCs and could promote the directional migration and growth of these cells.These findings indicate that the combination of a partition-type tubular scaffold,PDGF-MSs and MUSENPCs may be a promising model for the fabrication of tissue-engineered spinal cord grafts.

Locally controlled release of immunosuppressive promotes survival of transplanted adult spinal cord tissue

Transplantation of adult spinal cord tissue(aSCT)is a promising treatment for spinal cord injury(SCI)basing on various types of neural cells and matrix components inside aSCT.However,long-term systemic administration of immunosuppressors(e.g.tacrolimus,TAC)is required for the survival of allogeneic tissue,which often associated with severe side effects such as infection,liver damageand renal failure.In this study,a triglycerol monostearate(TGM)-based TAC delivery system(e.g.TAC@TGM)with high drug loading concentration was developed,which possessed injectable properties as well as sustainable and immune-responsive drug release behaviors.In complete transected SCI model,locally injected TAC@TGM could reduce the infiltration of inflammation cells,enhance the survival of transplanted aSCT(e.g.Tuj-1^(+)and NF^(+)neurons)and promote the recovery of locomotor function.Moreover,controlled release of TAC by TAC@TGM attenuated side effects of TAC on liver and kidneys compared with traditional systemic administration.More importantly,the developed TAC@TGM system provided a facile single dose of long-term immunosuppressive effect not just for aSCT transplantation,but also for other tissue/organ and cell transplantations.

Mechanism and effect of curcumin on apoptosis of EAE mice by regulating TLRs/NF-κB signaling pathway

Objective:To investigate theanti apoptosis effect of curcumin(cur)in experimental autoimmune encephalomyelitis(EAE)mice by regulating TLRs/NF-κB signaling pathway and its mechanism.Methods:45 C57BL/6 mice were randomly divided into the control group,EAE group,curcumin group,15 mice in each group.Blank groups are not processed.The EAE model was established by classical modeling method in the EAE group and the curcumin group.From the day of modeling,the blank group and the EAE group were intraperitoneally injected with 1ml/kg/d of normal saline,Curcumin group was given 100 mg/kg/d continuous intraperitoneal injection of curcumin extract.With Benson EAE group and Curcumin group mice were killed at the peak of the disease.The blank group and the rest of the mice were killed after 4 weeks of feeding,and the spinal cord tissue was taken out to separate the lumbar enlargement segment.The effects of curcumin on the pathological changes of spinal cord tissue in EAE mice were observed by HE staining and TUNEL staining,and the expression of apoptosis positive cells was calculated.The distribution and co aggregation of apoptosis related proteins Bcl-2 and Bax with spinal cord tissue were observed by double immunofluorescence staining The protein levels of TLR4,NF-κBp65 and MyD88 were detected by Western blot.Results:compared with the blank group,TUNEL staining increased the number of apoptotic cells and the apoptotic rate in EAE group(P<0.05);the expression of apoptosis related protein Bcl-2 decreased and the expression of Bax increased in EAE group(P<0.05),The protein of TLR4,NF-κBp65 and MyD88 in spinal cord tissue of mice were increased by blot detection(P<0.05);compared with EAE group,the number of apoptotic cells in spinal cord tissue of curcumin group was decreased by TUNEL staining,and the apoptosis rate was decreased(P<0.05);the expression of apoptosis related protein Bcl-2 was increased,the expression of Bax protein was decreased,and Western blot was used to detect the expression of apoptosis related protein The protein of TLR4,NF-κBp65 and MyD88 in spinal cord tissue of mice were decreased by blot(P<0.05).Conclusion:Curcumin has anti apoptotic effect on EAE mice,and its mechanism may be related to the inhibition of TLRs/NF-κB signaling pathway and the reduction of apoptotic protein production.