Cell Compatible Electrospun Poly(vinyl alcohol) Fibers for Tissue Regeneration

Poly(vinyl alcohol) (PVA) is a well known biocompatible synthetic polymer. PVA is not cell compatible due to its high hydrophilicity. As prepared by electrospinning in the form of nanofibers, it is unstable in aqueous environments including cell culture media. For tissue regeneration applications, this study demonstrates the use of PVA scaffold utilizing electrospun nanofibers with aqueous stability and cell compatibility toward creating biomaterial-tissue hybrid based medical devices. Two different approaches: heat treatment and ion beam treatment were developed to improve aqueous stability and promote cell compatibility for PVA fibers. Using a thermal annealing method at elevated temperatures, the fibers became stable in water. This observation correlated closely to the change in the crystallinity of PVA. Elastic moduli of individual fibers were determined using a multi-points bending approach by atomic force microscopy. Elastic moduli of as-spun PVA fibers were determined to be a function of fiber diameter and humidity. Significant changes in the elastic modulus of the modified PVA fibers were also observed. To improve the cell compatibility, low energy N+ and He+ ion beams were used to introduce amine and carbonyl functional groups. Cell compatibility was assessed in vitro using primary human skin fibroblasts (hsF). Confocal microscopy confirmed the adhesion and proliferation of hsF on both the random and aligned PVA fibers after the ion beam treatment, while cells failed to adhere to the untreated fibers. Cell morphology was observed to align and elongate along the fiber axis on aligned PVA fibers. After 10 days of proliferation, cells were found to form confluent layers and even multiple layers on the N+treated fibers. Cell proliferation depends on ion species, ion dose and fiber alignment. With the two post-processing treatments, PVA fibrous scaffold showed the potential to become biomaterial-tissue hybrid based medical devices for tissue regeneration applications

The comparative effects of metabolic surgery, SGLT2i, or GLP-1RA in patients with obesity and type 2 diabetes: a retrospective cohort study Corresponding

Background: New antidiabetic agents (sodium-glucose cotransporter-2 inhibitor [SGLT2i] and glucagon-like peptide-1 receptor agonist [GLP-1RA]) and metabolic surgery have protective effects on metabolic syndromes. Objectives: To compare the changes of metabolic parameters and costs among patients with obesity and type 2 diabetes undergoing metabolic surgery and initiating new antidiabetic agents over 12 months. Setting: Hong Kong Hospital Authority database from 2006 to 2017. Methods: This is a population-wide retrospective cohort study consisting of 2,616 patients (1,810 SGLT2i, 528 GLP-1RA, 278 metabolic surgery). Inverse probability treatment weighting of propensity score was applied to balance baseline covariates of patients with obesity and type 2 diabetes who underwent metabolic surgery, or initiated SGLT2i or GLP-1RA. Metabolic parameters and direct medical costs were measured and compared from baseline to 12 months in bariatric surgery, SGLT2i, and GLP-1RA groups. Results: Patients in all 3 groups had improved metabolic parameters over a 12-month period. Patients with metabolic surgery achieved significantly better outcomes in BMI (-5.39, -0.56, -0.40 kg/m2, p<0.001), % total weight loss (15.16%, 1.34%, 1.63%, p<0.001), systolic (-2.21, -0.59, 1.28 mmHg, p<0.001) and diastolic (-1.16, 0.50, -0.13 mmHg, p<0.001) blood pressure, HbA1c (-1.80%, -0.77%, -0.80%, p<0.001), triglycerides (-0.64, -0.11, -0.09 mmol/L, p<0.001), and estimated glomerular filtration rate (3.08, -1.37, -0.41 ml/min/1.73m2, p<0.001) after 12-month compared with patients with SGLT2i and GLP1-RA. Although the metabolic surgery group incurred the greatest direct medical costs (US$33,551, US$10,945, US$10,627, p<0.001), largely due to the surgery itself, the total monthly direct medical expenditure of metabolic surgery group became lower than that of SGLT2i and GLP1RA groups at 7 months. Conclusions: Beneficial weight loss and metabolic outcomes at 12-months were observed in all 3 groups, among which the metabolic surgery group showed the most remarkable effects but incurred the greatest medical costs. However, studies with a longer follow-up period are warranted to show long-term outcomes