Neethu Ninan

Pectin/carboxymethyl cellulose/microfibrillated cellulose composite scaffolds for tissue engineering

Highly porous three-dimensional scaffolds made of biopolymers are of great interest in tissue engineering applications. A novel scaffold composed of pectin, carboxymethyl cellulose (CMC) and microfibrillated cellulose (MFC) were synthesised using lyophilisation technique. The optimised scaffold with 0.1% MFC, C(0.1%), showed highest compression modulus (~3.987 MPa) and glass transition temperature (~103 °C). The pore size for the control scaffold, C(0%), was in the range of 30-300 μm while it was significantly reduced to 10-250 μm in case of C(0.1%). Using micro computed tomography, the porosity of C(0.1%) was estimated to be 88%. C(0.1%) showed excellent thermal stability and lower degradation rate compared to C(0%). The prepared samples were also characterised using XRD and FTIR. C(0.1%) showed controlled water uptake ability and in vitro degradation in PBS. It exhibited highest cell viability on NIH3T3 fibroblast cell line. These results suggest that these biocompatible composite scaffolds can be used for tissue engineering applications.

Antibacterial and wound healing analysis of gelatin/zeolite scaffolds.

In this article, gelatin/copper activated faujasites (CAF) composite scaffolds were fabricated by lyophilisation technique for promoting partial thickness wound healing. The optimised scaffold with 0.5% (w/w) of CAF, G (0.5%), demonstrated pore size in the range of 10-350 μm. Agar disc diffusion tests verified the antibacterial role of G (0.5%) and further supported that bacterial lysis was due to copper released from the core of CAF embedded in the gelatin matrix. The change in morphology of bacteria as a function of CAF content in gelatin scaffold was studied using SEM analysis. The confocal images revealed the increase in mortality rate of bacteria with increase in concentration of incorporated CAF in gelatin matrix. Proficient oxygen supply to needy cells is a continuing hurdle faced by tissue engineering scaffolds. The dissolved oxygen measurements revealed that CAF embedded in the scaffold were capable of increasing oxygen supply and thereby promote cell proliferation. Also, G (0.5%) exhibited highest cell viability on NIH 3T3 fibroblast cells which was mainly attributed to the highly porous architecture and its ability to enhance oxygen supply to cells. In vivo studies conducted on Sprague Dawley rats revealed the ability of G (0.5%) to promote skin regeneration in 20 days. Thus, the obtained data suggest that G (0.5%) is an ideal candidate for wound healing applications.

Faujasites Incorporated Tissue Engineering Scaffolds for Wound Healing: In Vitro and In Vivo Analysis

Exploring the possibility of using inorganic faujasites in tissue engineering scaffolds is a prospective approach in regenerative medicine. Novel gelatin/hyaluronic acid (HA)/faujasite porous scaffolds with low surface energy were fabricated by lyophilization. The pore size of gelatin/HA scaffold was 50-2000 μm, whereas it was greatly reduced to 10-250 μm after incorporation of 2.4% (w/w) of faujasites in polymer matrix, GH(2.4%). Micro computed tomography analysis showed that the porosity of GH(2.4%) was 90.6%. The summative effect was ideal for growth of dermal fibroblasts and cellular attachment. XRD analysis revealed that the embedded faujasites maintained their crystallinity in the polymer matrix even though they interacted with the polymers as indicated by FT-IR analysis. Coupling with effective reinforcement of faujasites, GH(2.4%) demonstrated compression modulus of 929 ± 7 Pa and glass transition temperature of 31 ± 0.05 °C. It exhibited controlled swelling and degradation, allowing sufficient space for tissue regrowth. The latter is further supported by capability of faujasites to provide efficient oxygen supply to fibroblast cells. GH(2.4%) showed a cell viability of 91 ± 8% on NIH 3T3 fibroblast cell lines. The in vivo studies on Sprague-Dawley rats revealed its ability to enhance wound healing by accelerating re-epithelization and collagen deposition. These findings indicated its potential as excellent wound dressing material.

Antibacterial and Anti-Inflammatory pH-Responsive Tannic Acid-Carboxylated Agarose Composite Hydrogels for Wound Healing

pH-sensitive hydrogels play an important role in controlled drug release applications and have the potential to impact the management of wounds. In this study, we report the fabrication of novel carboxylated agarose/tannic acid hydrogel scaffolds cross-linked with zinc ions for the pH-controlled release of tannic acid. The resulting hydrogels exhibited negligible release of tannic acid at neutral and alkaline pH and sustained release at acidic pH, where they also displayed maximum swelling. The hydrogels also displayed favorable antibacterial and anti-inflammatory properties, and a lack of cytotoxicity toward 3T3 fibroblast cell lines. In simulated wound assays, significantly greater cell migration and proliferation was observed for cells exposed to tannic acid hydrogel extracts. In addition, the tannic acid hydrogels were able to suppress NO production in stimulated human macrophages in a concentration-dependent manner, indicating effective anti-inflammatory activity. Taken together, the cytocompatibility, antibacterial, and anti-inflammatory characteristics of these novel pH-sensitive hydrogels make them promising candidates for wound dressings.

Natural Polymer/Inorganic Material Based Hybrid Scaffolds for Skin Wound Healing

Dermal tissue engineering focuses on the restoration of diseased and damaged tissues by using a combination of cells, biomaterials, and bioactive molecules. Inorganic substances like zeolites, clay, mesoporous silica, metals, and metal oxides are advanced materials used in wound healing research. They can improve the structural stability and bioactivity of bio polymeric scaffolds. Zeolites, clays, and mesoporous silica act as suitable carriers for drug delivery and when incorporated within scaffolds, serve as ideal matrices for promoting skin regeneration. This review focuses on various natural polymers/inorganic materials based composite scaffolds used for skin tissue engineering, highlighting their synthesis routes and mode of action by which wound healing is enhanced. Among the different inorganic materials used, the role of zeolites incorporated biocomposites for promoting blood coagulation, antibacterial effect; oxygen delivery to cells and wound healing are discussed in detail. The article thus includes recent attempts to explore the hidden potential of inorganic materials in dermal tissue engineering.

Wound healing in urology

Wound healing is a dynamic and complex phenomenon of replacing devitalized tissues in the body. Urethral healing takes place in four phases namely inflammation, proliferation, maturation and remodelling, similar to dermal healing. However, the duration of each phase of wound healing in urology is extended for a longer period when compared to that of dermatology. An ideal wound dressing material removes exudate, creates a moist environment, offers protection from foreign substances and promotes tissue regeneration. A single wound dressing material shall not be sufficient to treat all kinds of wounds as each wound is distinct. This review includes the recent attempts to explore the hidden potential of growth factors, stem cells, siRNA, miRNA and drugs for promoting wound healing in urology. The review also discusses the different technologies used in hospitals to treat wounds in urology, which make use of innovative biomaterials synthesised in regenerative medicines like hydrogels, hydrocolloids, foams, films etc., incorporated with growth factors, drug molecules or nanoparticles. These include surgical zippers, laser tissue welding, negative pressure wound therapy, and hyperbaric oxygen treatment.

Carbon Nanotube Tube Filled Polymer Nanocomposites and Their Applications in Tissue Engineering

Abstract Carbon nanotubes (CNTs) that belong to the family of fullerenes are considered as building blocks of nanotechnology. There has been intense interest in reinforced composites made with CNTs because of their unusual physical properties and large application potential, covering a broad range in nanotechnology. With their remarkable tensile strength, high resilience, flexibility, and other superlative electrical and physico-chemical properties, CNTs have been of paramount importance to researchers in recent years. Their large surface area together with the above mentioned properties have also made CNTs and their derivatives very attractive potential candidates for nanoelectronics, nanolithography, composite materials, sensors, optical actuators, biomolecular recognition, and biomedical applications, including DNA-modification, drug delivery, and gene delivery. This chapter will give an insight into preparation, properties and types of CNTs; their application in improving the mechanical, rheological, thermal and electrical properties of composites. It also discusses in detail how CNTs based composites are used in tissue engineering and explore their cell compatibility.

Chapter 13 – Upconversion Nanoparticles

Upconversion is an optical process that converts low energy pump photons to high energy pump photons. Surface-modified upconversion nanoparticles (UCNPs) are used for several biomedical applications. Compared to quantum dots, organic flurophores, gold nanoparticles, and other bioimaging agents, UCNPs have low toxicity, high photostability, and show sharp emission wavelength. The intense visible emission from these nanoparticles come under near-infrared region and is not detrimental to biological samples. In this chapter, we review recent advancements of UCNPs in drug delivery, bioimaging, and biological detection, bringing to the forefront the characteristics, strengths, and weakness of these nanoparticles.

Dermal Tissue Engineering: Current Trends

Skin defects resulting from trauma, burns, and disease can cause skin necrosis and other chronic disorders. For the treatment of skin injuries, several strategies are currently adopted. Although they are proven to be clinically effective, these strategies face several challenges like inadequate vascularization, poor adherence to wound site, high cost, and inability to synthesize skin appendages. This chapter summarizes the progress of engineered skin substitues, reviews some critical aspects of skin biology, and highlights future developments that need to be undertaken for synthesizing bioengineered skin. The article gives insight on nanotopography-guided skin tissue engineering and stem cell therapy. The merits and demerits of fetal tissue engineering for scarless wound therapy are also discussed in detail.

3D Scaffolding for Pancreatic Islet Replacement

Although islet transplantation is emerging as a critical solution for type I diabetes, it faces several problems like long-term independence of insulin, donor supply, immune rejection, and cell viability. Around two-thirds of the transplanted islets die in the first few days of the posttransplant and during the time in which remaining islets become functional, hyperglycemia eventually returns as islets are lost. The infused islets may coagulate and may lead to instant blood-mediated inflammatory reaction that causes extensive islet damage during transplantation. The researchers are now focusing on developing three-dimensional scaffolds that promote islet survival and growth and to achieve prolonged insulin independence for patients suffering from type I diabetes. This chapter focuses on the recent developments in 3D scaffolding to support pancreatic islet transplantation.