Injectable conductive gelatin methacrylate/oxidized dextran hydrogel encapsulating umbilical cord mesenchymal stem cells for myocardial infarction treatment

Umbilical cord mesenchymal stem cells(UCMSCs)transplantation has been proposed as a promising treatment modality for myocardial infarction(MI),but the low retention rate remains a considerable challenge.Injectable natural polymer hydrogels with conductivity ability are highly desirable as cell delivery vehicles to repair infarct myocardium and restore the cardiac function.In this work,we developed a hydrogel system based on gelatin methacrylate(GelMA)and oxidized dextran(ODEX)as cell delivery vehicles for MI.And dopamine could be used as a reductant of graphene oxide(GO)to form reductive GO(rGO).By adjusting the amount of rGO,the conductivity of hydrogels with 0.5 mg/mL rGO concentration(≈10^(-4)S/cm)was similar to that of natural heart tissue.In vitro cell experiments showed that the prepared hydrogels had excellent biocompatibility and cell delivery ability of UCMSCs.More importantly,GelMA-O5/rGO hydrogel could promote UCMSCs growth and proliferation,improve the myocardial differentiation ability of UCMSCs,and up-regulate the expression of cTnI and Cx43.Further in vivo experiments demonstrated that GelMA-O5/rGO/UCMSCs Hydrogel could significantly improve the ejection fraction(EF)of rats and significantly reduce myocardial infarct area compared to PBS group,promote the survival of UCMSCs,enhance the expression level of cTnI and Cx43,and decrease the expression level of caspase-3.The findings of this study suggested that the injectable conductive GelMA-O5/rGO hydrogel encapsulating UCMSCs could improve damaged myocardial tissue and reconstruct myocardial function,which will be a promising therapeutic strategy for cardiac repair.

Study of locust bean gum reinforced cyst-chitosan and oxidized dextran based semi-IPN cryogel dressing for hemostatic application

Severe blood loss due to traumatic injuries remains one of the leading causes of death in emergency settings.Chitosan continues to be the candidate material for hemostatic applications due to its inherent hemostatic properties.However,available chitosan-based dressings have been reported to have an acidic odor at the wound site due to the incorporation of acid based solvents for their fabrication and deformation under compression owing to low mechanical strength limiting its usability.In the present study semi-IPN cryogel was fabricated via Schiff's base cross-linking between the polyaldehyde groups of oxidized dextran and thiolated chitosan in presence of locust bean gum(LBG)known for its hydrophilicity.Polymerization at
12C yielded macroporous semi-IPN cryogels with an average pore size of 124.57±20.31 mm and 85.46%porosity.The hydrophobicity index of LBG reinforced semi-IPN cryogel was reduced 2.42 times whereas the swelling ratio was increased by 156.08%compare to control cryogel.The increased hydrophilicity and swelling ratio inflated the compressive modulus from 28.1 kPa to 33.85 for LBG reinforced semi-IPN cryogel.The structural stability and constant degradation medium pH were also recorded over a period of 12 weeks.The cryogels demonstrated lower adsorption affinity towards BSA.The cytotoxicity assays(direct,indirect)with 3T3-L1 fibroblast cells confirmed the cytocompatibility of the cryogels.The hemolysis assay showed<5%hemolysis confirming blood compatibility of the fabricated cryogel,while whole blood clotting and platelet adhesion assays confirmed the hemostatic potential of semi-IPN cryogel.

Multifunctional dextran micelles as drug delivery carriers and magnetic resonance imaging probes

Multifunctional nanoparticles combining diagnostic and therapeutic agents into a single platform make cancer theranostics possible and have attracted wide interests in the field. In this study, a multifunctional nanocomposite based on dextran and superparamagnetic iron oxide nanoparticles （SPIO） was prepared for drug delivery and magnetic resonance imaging （MRI）. Amphiphilic dextran was synthesized by grafting stearyl acid onto the carbohydrate backbone, and micelle was formed by the resulted amphiphilic dextran with low critical micelle concentration at 1.8 mg L^-1. Doxorubicin （DOX） and a cluster of the manganese-doped iron oxide nanoparticles （Mn-SPIO） nanocrystals were then coencapsulated successfully inside the core of dextran micelles, resulting in nanocomposites with diameter at about 100 nm. Cell culture experiments demonstrated the potential of these Mn-SPIO/DOX nanocomposites as an effective multifunctional nanoplat- lk）rm for the delivery of anticancer drug DOX with a loading content （DLC） of 16 %. Confocal laser scanning microscopy reveals that the Mn-SPIO/DOX had excellent internalization ability against MCF-7/Adr cells after 2-h labeling compared with flee DOX.HCI. Under a 3.0-T MRI scanner, Mn-SPIO/ DOX nanocomposite-labeled cells in gelatin phantom show much darker images than the control. Their transverse relaxation （T2） rate is also significantly higher than that of the control cells （33.9 versus 2.3 s^-1）. Our result offers an effective strategy to treat MCF-7/Adr at optimized low dosages with imaging capability.