Electrospun scaffolds functionalized with heparin and vascular endothelial growth factor increase the proliferation of endothelial progenitor cells.

In severe cases of peripheral arterial disease, tissue loss can occur and the use of vascular grafts can be necessary. However, currently, there are no suitable substitutes for application in small diameter vessels. The aim of this work has been to produce scaffolds with adequate properties for application as vascular substitutes. Polycaprolactone scaffolds were produced by the electrospinning technique. The surface of the scaffolds was functionalized with heparin and vascular endothelial growth factor (VEGF) and their physical-chemical properties were characterized. Human endothelial progenitor cells (EPCs) or mesenchymal stem cells (MSCs) were seeded onto the surface of the scaffolds in order to create an endothelial layer. The electrospun scaffolds exhibited mechanical properties compatible with the native arteries. The presence of heparin prevented blood coagulation on the scaffold surface. The presence of heparin and VEGF favored the adaptation of MSCs and EPCs on the scaffolds in relation to the non functionalized scaffolds. In addition, the EPCs cultivated on the scaffolds maintained the expression of CD31, CD34 and VE-cadherin genes. The results obtained in the present study suggest that electrospun scaffolds functionalized with heparin and VEGF can be applied in vascular tissue engineering. These scaffolds exhibited antithrombogenic properties and favored the development of cells on their surface. The association of heparin and VEGF with electrospun scaffolds increased EPC proliferation, favoring the formation of the endothelial layer and the regeneration of damaged vessels.

Bio-electrospraying of human mesenchymal stem cells: An alternative for tissue engineering.

Bio-electrospraying (BES) is a technique used for the processing of cells and can be applied to tissue engineering. The association of BES with scaffold production techniques has been shown to be an interesting strategy for the production of biomaterials with cells homogeneously distributed in the entire structure. Various studies have evaluated the effects of BES on different cell types. However, until the present moment, no studies have evaluated the impact of BES time on mesenchymal stem cells (MSC). Therefore, the aim of this work was to standardise the different parameters of BES (voltage, flow rate, and distance of the needle from the collecting plate) in relation to cell viability and then to evaluate the impact of BES time in relation to viability, proliferation, DNA damage, maintenance of plasticity and the immunophenotypic profile of MSC. Using 15 kV voltage, 0.46 ml/h flow rate and 4 cm distance, it was possible to form a stable and continuous jet of BES without causing a significant reduction in cell viability. Time periods between 15 and 60 min of BES did not cause alterations of viability, proliferation, plasticity, and immunophenotypic profile of the MSC. Time periods above 30 min of BES resulted in DNA damage; however, the DNA was able to repair itself within five hours. These results indicate that bio-electrospraying is an adequate technique for processing MSC which can be safely applied to tissue engineering and regenerative medicine.

Role of autologous mesenchymal stem cells associated with platelet-rich plasma on healing of cutaneous wounds in diabetic mice.

BACKGROUND: Chronic cutaneous lesions affect 15% of human patients with diabetes, and the associated risk of limb amputations is 15-46 times greater than that of people with normal glycaemia. It is estimated that half of these limb amputations could be avoided by opportune treatment with somatic stem cells or platelet-rich plasma (PRP). METHODS: We evaluated the effects of autologous transplant of mesenchymal stem cells (MSCs) with or without combination with autologous PRP in the re-epithelialization of cutaneous lesions induced in diabetic mice. RESULTS: Animals treated with MSCs alone showed a similar level of re-epithelialization of cutaneous lesions to those treated with MSC plus PRP, and no significant difference was found between the two treatments. CONCLUSION: Both treatments gave better results than daily cleaning of the cutaneous lesions with saline or covering of the lesions with semipermeable adherent bandage.

Co-transplantation of mesenchymal stem cells maintains islet organisation and morphology in mice.

AIMS/HYPOTHESIS: Recent studies have shown that mesenchymal stem cells (MSCs) secrete several factors that improve survival and function of transplanted islets. Implantation of islets beneath the kidney capsule results in morphological changes, due to interactions of the graft with the host, thus impairing islet function. We co-transplanted MSCs with islets to determine their effects on the remodelling process and studied graft function in a mouse model of minimal islet mass. METHODS: Islets were syngeneically transplanted, either alone or with kidney-derived MSCs, underneath the kidney capsule of streptozotocin-induced diabetic C57Bl/6 mice. Blood glucose levels were monitored and intraperitoneal glucose tolerance tests carried out. Hormone contents of grafts and pancreas were assessed by radioimmunoassay. Graft morphology and vascularisation were evaluated by immunohistochemistry. RESULTS: MSCs improved the capacity of islet grafts to reverse hyperglycaemia, with 92% of mice co-transplanted with MSCs reverting to normoglycaemia, compared with 42% of those transplanted with islets alone. Average blood glucose concentrations were lower throughout the 1 month monitoring period in MSC co-transplanted mice. MSCs did not alter graft hormone content. Islets co-transplanted with MSCs maintained a morphology that more closely resembled that of islets in the endogenous pancreas, both in terms of size, and of endocrine and endothelial cell distribution. Vascular engraftment was superior in MSC co-transplanted mice, as shown by increased endothelial cell numbers within the endocrine tissue. CONCLUSIONS/INTERPRETATION: Co-transplantation of islets with MSCs had a profound impact on the remodelling process, maintaining islet organisation and improving islet revascularisation. MSCs also improved the capacity of islets to reverse hyperglycaemia.

Association between the 1858T allele of the protein tyrosine phosphatase nonreceptor type 22 and type 1 diabetes in a Brazilian population.

The 1858T allele of the protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene has been associated to diabetes in different populations. We investigated a possible relationship between this polymorphism and type 1 diabetes in a cohort of Brazilian patients. A significantly higher frequency of the 1858T allele was observed in diabetic patients (n = 211) than in control individuals (n = 241). Additionally, the heterozygote genotype was also increased in the diabetic group. No association was observed between the PTPN22 T allele and gender, or between T carriers and age of onset of T1D. This work describes for the first time a strong association of the 1858T allele with type 1 diabetes in a Brazilian population, reinforcing the role of this variant as an important susceptibility factor for this disease.