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Autologous graft replacement as a strategy to treat diseased peripheral small diameter (≤6 mm) blood vessel is often challenged by prior vein harvesting. To address this issue, we fabricated native-tissue mimicking multilayered small diameter vascular graft (SDVG) using mulberry (Bombyx mori) and Indian endemic non-mulberry (Antheraea assama and Philosamia ricini) silk. Patterned silk films were fabricated on microgrooved PDMS mold, casted by soft lithography. The biodegradable patterned film templates with aligned cell sheets were rolled onto an inert mandrel to mimic vascular conduit. The hemocompatible and mechanically strong non-mulberry films with RGD motif supported ∼1.2 folds greater proliferation of vascular cells with aligned anchorage. Elicitation of minimal immune response on subcutaneous implantation of the films in mice was complemented by ∼45% lower TNF α secretion by in vitro macrophage culture post 7 days. Pattern-induced alignment favored the functional contractile phenotype of smooth muscle cells (SMCs), expressing the signature markers-calponin, α-smooth muscle actin (α-SMA), and smooth muscle myosin heavy chain (SM-MHC). Endothelial cells (ECs) exhibited a typical punctuated pattern of von Willebrand factor (vWF). Deposition of collagen and elastin by the SMCs substantiated the aptness of the graft with desired biomechanical attributes. Furthermore, the burst strength of the fabricated conduit was in the range of ∼915-1260 mmHg, a prerequisite to withstand physiological pressure. This novel fabrication approach may eliminate the need of maturation in a pulsatile bioreactor for obtaining functional cellular phenotype. This work is thereby an attestation to the immense prospects of exploring non-mulberry silk for bioengineering a multilayered vascular conduit similar to a native vessel in "form and function", befitting for in vivo transplantation.

Pure hydroxyapatite (HAp) and a biphasic calcium phosphate [containing 90% of beta-tri-calcium phosphate (beta-TCP) and 10% HAp] were tailored through an aqueous solution combustion synthesis. Porous struts were prepared using all the powders along with bioglass, a known bioactive material, and subsequently characterized. Sterilized struts were implanted to the lateral side of radius bone of 24 black Bengal goats of either sex, in which a blank hole was left unfilled in a group of six specimens to act as control. The bone formation response of the three implanting materials in vivo has been studied using scanning electron microscope and histological analysis in contrast with positive controls. Push-out tests were used to assess the mechanical strength at the bone-biomaterial interface. It was observed that interfacial response was strongly dependent on combinations of different physical and chemical parameters. The surface of beta-TCP exhibited similar characteristics of bone and was distinct from those of intervening apatite layer of bioglass. Lower bone ingrowth and reduced strength was observed with HAp compared to beta-TCP/bioglass-based implants. Bone formation response of the Ca-P material varied according to the composition of the implanting material, which could be tailored through this novel synthesis.

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Chronic cutaneous ulcers, a complex pathophysiological diabetic condition, represent a critical clinical challenge in the current diabetes mellitus pandemic. Consequently, there is a compelling need for bioactive dressings that can trigger healing processes for complete wound repair. Silk fibroin (SF), a natural protein polymer from mulberry and non-mulberry silkworms, has properties that support accelerated wound healing rate. SF from non-mulberry variety possesses additional cell-binding motifs (arginine, glycine, and aspartate), offering cell-material interactions. This study is aimed to investigate wound healing efficacy of dressings made up of various SF varieties blended with poly(vinyl alcohol) biopolymer in alloxan-induced diabetic rabbit model. The nanofibrous mats have been developed using electrospinning and functionalized with growth factors and LL-37 antimicrobial peptide for sustained delivery. Following post 14-day treatment, non-mulberry SF (NMSF)-based dressings healed the wounds faster, in comparison with their mulberry Bombyx mori SF, poly(vinyl alcohol), and control counterparts (p < .01). NMSF-based dressings also supported faster granulation tissue development, angiogenesis, and reepithelialization of wounds. Gene expression study of matrix metalloproteinases and collagen proteins affirmed higher extent of tissue remodelling during the repair process. Furthermore, there was organized extracellular matrix deposition (collagen type I, collagen type III, elastin, and reticulin) and higher wound breaking strength in NMSF compared with other groups after 4 weeks. These results validated the potential of NMSF-based bioactive dressings to regulate extracellular matrix deposition leading to faster and complete repair of chronic diabetic cutaneous wounds.

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