Arun Kumar Teotia

Electricity from the silk cocoon membrane.

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management.

Gelatin-Modified Bone Substitute with Bioactive Molecules Enhance Cellular Interactions and Bone Regeneration.

In this work, we have synthesized injectable bone cement incorporated with gelatin to enhance cellular interaction. Human osteosarcoma Saos-2 cells derived bone morphogenetic proteins (BMPs) and a bisphosphonate (zoledronic acid (0.2 mM)) were also incorporated to cement. In vitro studies conducted using Saos-2 demonstrated enhanced cell proliferation on gelatin (0.2%w/v) cement. The differentiation of C2C12 mouse myoblast cells into bone forming cells showed 6-fold increase in ALP levels on gelatin cement. Polymerase chain reaction (PCR) for bone biomarkers showed osteoinductive potential of gelatin cement. We investigated efficacy for local delivery of these bioactive molecules in enhancing bone substitution qualities of bone cements by implanting in 3.5 mm critical size defect in tibial metaphysis of wistar rats. The rats were sacrificed after 12 weeks and 16 weeks post implantation. X-ray, micro-CT, histology, and histomorphometry analysis were performed to check bone healing. The cement materials slowly resorbed from the defect site leaving HAP creating porous matrix providing surface for bone formation. The materials showed high biocompatibility and initial bridging was observed in all the animals but maximum bone formation was observed in animals implanted with cement incorporated with zoledronic acid followed by cement with BMPs compared to other groups.

Nano-Hydroxyapatite Bone Substitute Functionalized with Bone Active Molecules for Enhanced Cranial Bone Regeneration

The aim of this study was to synthesize and characterize a nano-hydroxyapatite (nHAP) and calcium sulfate bone substitute (NC) for cranioplasty. The NC was functionalized with low concentrations of bone morphogenetic protein-2 (BMP-2) and zoledronic acid (ZA) and characterized both in vitro and in vivo. In vitro studies included MTT, ALP assays, and fluorescent staining of Saos-2 (human osteoblasts) and MC3T3-E1 (murine preosteoblasts) cells cultured on NC. An in vivo study divided 20 male Wistar rats into four groups: control (defect only), NC, NC + ZA, and NC + ZA + rhBMP-2. The materials were implanted in an 8.5 mm critical size defect in the calvarium for 12 weeks. Micro-CT quantitative analysis was carried out in vivo at 8 weeks and ex vivo after 12 weeks. Mineralization was highest in the NC + ZA + rhBMP-2 group (13.0 ± 2.8 mm3) compared to the NC + ZA group (9.0 ± 3.2 mm3), NC group (6.4 ± 1.9 mm3), and control group (3.4 ± 1.0 mm3) after 12 weeks. Histological and spectroscopic analysis of the defect site provided a qualitative confirmation of neo-bone, which was in agreement with the micro-CT results. In conclusion, NC can be used as a carrier for bioactive molecules, and functionalization with rhBMP-2 and ZA in low doses enhances bone regeneration.

Biocomposite macroporous cryogels as potential carrier scaffolds for bone active agents augmenting bone regeneration.

Osteoinduction can be enhanced by combining scaffolds with bone morphogenic protein-2 (BMP-2). However, BMPs are known to also cause bone resorption. This can be controlled using bisphosphonates like zoledronic acid (ZA). In this study, we produced two different scaffolds containing silk-fibroin, chitosan, agarose and hydroxyapatite (HA) with and without bioactive glass. The aims of the study were to fabricate, physico-chemically characterize and evaluate the carrier properties of the scaffolds for recombinant human BMP-2 (rhBMP-2) and ZA. Scaffolds were characterized using various methods to confirm their composition. During cell-material interactions, both scaffolds exhibited gradual but sustained proliferation of both C2C12 and MSCs for a period of 6weeks with augmentative effects on their phenotype indicated by elevated levels of alkaline phosphatase (ALP) cuing towards osteogenic differentiation. In-vitro effects of rhBMP-2 and ZA contained within both the scaffolds was assessed on MC3T3 preosteoblast cells and the results show a significant increase in the ALP activity of the cells seeded on scaffolds with rhBMP-2. Further, the scaffold with both HA and bioactive glass was considered for the animal study. In-vitro, this scaffold released nearly 25% rhBMP-2 in 21-days and the addition of ZA did not affect the release. In the animal study, the scaffolds were combined with rhBMP-2 and ZA, rhBMP-2 or implanted alone in an ectopic muscle pouch model. Significantly higher bone formation was observed in the scaffold loaded with both rhBMP-2 and ZA as seen from micro-computed tomography, histomorphometry and energy dispersive X-ray spectroscopy.

Decellularized Liver Matrix-Modified Cryogel Scaffolds as Potential Hepatocyte Carriers in Bioartificial Liver Support Systems and Implantable Liver Constructs

Recent progress in the use of decellularized organ scaffolds as regenerative matrices for tissue engineering holds great promise in addressing the issue of donor organ shortage. Decellularization preserves the mechanical integrity, composition, and microvasculature critical for zonation of hepatocytes in the liver. Earlier studies have reported the possibility of repopulating decellularized matrices with hepatic cell lines or stem cells to improve liver regeneration. In this work, we study the versatility of the decellularized liver matrix as a substrate coating of three-dimensional cryogel scaffolds. The coated cryogels were analyzed for their ability to maintain hepatic cell growth and functionality in vitro, which was found to be significantly better than the uncoated cryogel scaffolds. The decellularized liver matrix-coated cryogel scaffolds were evaluated for their potential application as a cell-loaded bioreactor for bioartificial liver support and as an implantable liver construct. Extracorporeal connection of the coated cryogel bioreactor to a liver failure model showed improvement in liver function parameters. Additionally, offline clinical evaluation of the bioreactor using patient-derived liver failure plasma showed its efficacy in improving liver failure conditions by approximately 30-60%. Furthermore, implantation of the decellularized matrix-coated cryogel showed complete integration with the native tissue as confirmed by hematoxylin and eosin staining of tissue sections. HepG2 cells and primary human hepatocytes seeded in the coated cryogel scaffolds implanted in the liver failure model maintained functionality in terms of albumin synthesis and cytochrome P450 activity post 2 weeks of implantation. In addition, a 20-60% improvement in liver function parameters was observed post implantation. These results, put together, suggest a possibility of using the decellularized matrix-coated cryogel scaffolds for liver tissue engineering applications.

Mesenchymal stromal cell-derived exosome-rich fractionated secretome confers a hepatoprotective effect in liver injury

BackgroundMesenchymal stromal cells (MSCs) are an attractive therapeutic agent in regenerative medicine. Recently, there has been a paradigm shift from differentiation of MSCs to their paracrine effects at the injury site. Several reports elucidate the role of trophic factors secreted by MSCs toward the repair of injured tissues. We hypothesize that fractionating the MSC secretome will enrich exosomes containing soluble bioactive molecules, improving its therapeutic potential for liver failure.MethodsRat bone marrow MSCs were isolated and the conditioned media filtered, concentrated and ultracentrifuged to generate fractionated secretome. This secretome was characterized for the presence of exosomes and recovery from liver injury assessed in in-vitro liver injury models. The results were further validated in vivo.ResultsStudies on in-vitro liver injury models using acetaminophen and hydrogen peroxide show better cell recovery and reduced cytotoxicity in the presence of fractionated as opposed to unfractionated secretome. Further, the cells showed reduced oxidative stress in the presence of fractionated secretome, suggesting a potential antioxidative effect. These results were further validated in vivo in liver failure models, wherein improved liver regeneration in the presence of fractionated secretome (0.819 ± 0.035) was observed as compared to unfractionated secretome (0.718 ± 0.042).ConclusionsThe work presented is a proof of concept that fractionating the secretome enriches certain bioactive molecules involved in the repair and recovery of injured liver tissue.Graphical abstractExosome enriched mesenchymal stromal cell-derived fractionated secretome potentiates recovery upon injection in injured liver

Mechanically tuned nanocomposite coating on titanium metal with integrated properties of biofilm inhibition, cell proliferation, and sustained drug delivery

The clinical success of coated implants in executing biological functions inclusive of sustainable drug release and long term antibacterial activity without antibiotics is critical. To this aim, a nanohybrid of silver nanoparticles (AgNPs) cored in polyvinyl alcohol nanocapsules (Ag-PVA NCs) embedded in chitosan (CS) matrix loaded with anti-inflammatory drug naproxen was prepared. The synthesized nanohybrids that were subjected to coatings on (3-aminopropyl)triethoxysilane (APTES) treated titanium (Ti) metal exhibited dual role of excellent inhibition on biofilm formation and sustained drug release. These dual characteristics are achieved mainly based on intrinsic antibacterial property of AgNPs and differential entrapment of drug in PVA polymeric shell of AgNPs and CS matrix. The coatings also demonstrated enhanced mechanical properties with increasing inorganic filler and stress shielding on Ti metal. The biocompatibility tests involving adhesion, proliferation and differentiation of osteoblast cells demonstrated the efficacy of Ag-PVA NCs embedded in CS matrix as a suitable coating material for orthopedic applications.

Characterisation of porous knitted titanium for replacement of intervertebral disc nucleus pulposus

Effective restoration of human intervertebral disc degeneration is challenged by numerous limitations of the currently available spinal fusion and arthroplasty treatment strategies. Consequently, use of artificial biomaterial implant is gaining attention as a potential therapeutic strategy. Our study is aimed at investigating and characterizing a novel knitted titanium (Ti6Al4V) implant for the replacement of nucleus pulposus to treat early stages of chronic intervertebral disc degeneration. Specific knitted geometry of the scaffold with a porosity of 67.67 ± 0.824% was used to overcome tissue integration failures. Furthermore, to improve the wear resistance without impairing original mechanical strength, electro-polishing step was employed. Electro-polishing treatment changed a surface roughness from 15.22 ± 3.28 to 4.35 ± 0.87 µm without affecting its wettability which remained at 81.03 ± 8.5°. Subsequently, cellular responses of human mesenchymal stem cells (SCP1 cell line) and human primary chondrocytes were investigated which showed positive responses in terms of adherence and viability. Surface wettability was further enhanced to super hydrophilic nature by oxygen plasma treatment, which eventually caused substantial increase in the proliferation of SCP1 cells and primary chondrocytes. Our study implies that owing to scaffolds physicochemical and biocompatible properties, it could improve the clinical performance of nucleus pulposus replacement.