Synthesis and fabrication of novel quinone-based chromenopyrazole antioxidant-laden silk fibroin nanofibers scaffold for tissue engineering applications.

Oxidative stress is critically attributed for impeding tissue repair and regeneration process. Elimination of over-accumulated, deleterious reactive oxygen species (ROS) could be elicited to accelerate healing in tissue engineering applications. Antioxidant biomolecules play a pivotal role in attenuating oxidative stress by neutralizing the free radical effects. Herein, we describe the synthesis and fabrication of novel quinone-based chromenopyrazole (QCP) antioxidant-laden silk fibroin (SF) electrospun nanofiber scaffold (QCP-SF) for tissue engineering applications. The spectral characterization of the synthesized compounds (6a-6h) were analysed by using NMR, FTIR and mass spectra and cell viability study of all the synthesized compounds were evaluated by MTT assay in primary rat bone marrow stem cells (rBMSCs). Among the prepared molecules, compound 6h showed an excellent cell viability, and antioxidant efficacy of compound 6h (QCP) was investigated through 1,1­diphenyl­2­picrylhydiazyl (DPPH) scavenging assay. QCP expressed high antioxidant activity with IC50% of DPPH scavenging was observed about 5.506 ±â€¯0.2786 µg. Novel QCP laden SF fiber scaffolds (QCP-SF) were characterized and incorporation of QCP did not affect the nanofiber architecture of QCP-SF scaffold. QCP-SF scaffold exhibited an enhanced thermal and mechanical stability when compared to native SF fiber mat. In vitro biocompatibility studies were evaluated using NIH 3T3 fibroblasts and rBMSCs. The QCP-SF scaffold displayed an increased cell attachment and proliferation in both cell types. In vitro wound healing study (scratch assay) of QCP-SF scaffold showed an excellent cell migration with NIH 3T3 cells into scratch area and complete cell migration occurred within 24 h. Based on results, we propose that QCP-loaded SF (QCP-SF) nanofibrous scaffolds can serve as a promising potential antioxidant fibrous scaffold for skin tissue engineering applications.

Nanosecond laser ablation enhances cellular infiltration in a hybrid tissue scaffold.

Hybrid tissue engineered (HTE) scaffolds constituting polymeric nanofibers and biological tissues have attractive bio-mechanical properties. However, they suffer from small pore size due to dense overlapping nanofibers resulting in poor cellular infiltration. In this study, using nanosecond (ns) laser, we fabricated micro-scale features on Polycaprolactone (PCL)-Chitosan (CH) nanofiber layered bovine pericardium based Bio-Hybrid scaffold to achieve enhanced cellular adhesion and infiltration. The laser energy parameters such as fluence of 25J/cm2, 0.1mm instep and 15 mark time were optimized to get structured microchannels on the Bio-Hybrid scaffolds. Laser irradiation time of 40µs along with these parameters resulted in microchannel width of ~50µm and spacing of ~35µm between adjacent lines. The biochemical, thermal, hydrophilic and uniaxial mechanical properties of the Bio-Hybrid scaffolds remained comparable after laser ablation reflecting extracellular matrix (ECM) stability. Human umbilical cord mesenchymal stem cells and mouse cardiac fibroblasts seeded on these laser-ablated Bio-Hybrid scaffolds exhibited biocompatibility and increased cellular adhesion in microchannels when compared to non-ablated Bio-Hybrid scaffolds. These findings suggest the feasibility to selectively ablate polymer layer in the HTE scaffolds without affecting their bio-mechanical properties and also describe a new approach to enhance cellular infiltration in the HTE scaffolds.

Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44+, αSMA+, Vimentin+ and CD105- human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children.

Cystic fibrosis in a retro-positive child.

We present a rare association of cystic fibrosis and retro positivity in a grossly malnutrited child. The child had pulmonary, pancreatic and colonic manifestations with superadded herpes simplex virus interstitial pneumonia and lymphocytic meningitis.