Enhanced bioactive scaffolds for bone tissue regeneration

Bone injuries are commonly termed as fractures and they vary in their severity and causes. If the fracture is severe and there is loss of bone, implant surgery is prescribed. The response to the implant depends on the patient\u27s physiology and implant material. Sometimes, the compromised physiology and undesired implant reactions lead to post-surgical complications. [4, 5, 20, 28] Efforts have been directed towards the development of efficient implant materials to tackle the problem of post-surgical implant failure. [ 15, 19, 24, 28, 32] The field of tissue engineering and regenerative medicine involves the use of cells to form a new tissue on bio-absorbable or inert scaffolds. [2, 32] One of the applications of this field is to regenerate the damaged or lost bone by using stem cells or osteoprogenitor cells on scaffolds that can integrate in the host tissue without causing any harmful side effects. [2, 32] A variety of natural, synthetic materials and their combinations have been used to regenerate the damaged bone tissue. [2, 19, 30, 32, 43] Growth factors have been supplied to progenitor cells to trigger a sequence of metabolic pathways leading to cellular proliferation, differentiation and to enhance their functionality. [56, 57] The challenge persists to supply these proteins, in the range of nano or even picograms, and in a sustained fashion over a period of time. A delivery system has yet to be developed that would mimic the body\u27s inherent mechanism of delivering the growth factor molecules in the required amount to the target organ or tissue. Titanium is the most preferred metal for orthopedic and orthodontic implants. [28, 46, 48] Even though it has better osteogenic properties as compared to other metals and alloys, it still has drawbacks like poor integration into the surrounding host tissue leading to bone resorption and implant failure. [20, 28, 35] It also faces the problem of postsurgical infections that contributes to the implant failure. [26, 37] The focus of this dissertation was to design and develop novel implant materials for coating titanium to improve its biological properties. These natural and/or semi-synthetic materials improved cellular adhesion, biological response to the scaffolds and prevented growth of bacteria when they were enhanced with growth factor and anti-infective loaded nanotubes. The implant materials showed promise when tested in vitro for cell proliferation, differentiation and bacterial growth inhibition

ATTENUATION OF IRON OVERLOAD AND EFFECT OF ANTIOXIDANTS SUPPLEMENTATION ON OXIDATIVE STRESS IN HOMOZYGOUS β-THALASSEMIA

It has been projected that ferritin and iron yoke in homozygous thalassemic children is coupled with the enhanced free radical formation and blemished in antioxidative defense coordination. Aim: The purpose of the current study was to analyze the consequence of serum iron, erythrocyte catalase, and erythrocyte superoxide dismutase (ESOD) in patients with beta-thalassemia major. Method: 60 beta-thalassemia major patients were studied before and after supplementation of A – Z antioxidants for 20 weeks, and status were compared with 60 age and sex-matched healthy normal.    Serum Iron estimation was carried out by Ramsay’s Dipyridyl Method. Estimation of erythrocyte superoxide dismutase was done by Kajari Das Method. The levels of Catalase concentration in erythrocytes were analyzed by the Goth method.  All the objectives mentioned above were run by using a UV visible Spectrophotometer (Systronix). Results: A marked enhancement was seen in the intensity of serum iron, and superoxide dismutase (p<0.001) with parallel decline was observed in the level of erythrocyte catalase (p<0.001) in homozygous thalassemia patients when compared with healthy subjects. After 20 weeks of regular supplementation of antioxidants A-Z syrup, which consists of multimineral multivitamins, the concentration of catalase was increased whereas iron and ESOD (p<0.001) were reduced significantly when compared with normal and baselines thalassemic patients. Conclusion: Due to multiple blood transfusions, beta-thalassemia major children are at advanced risk due to secondary iron surplus and intense oxidative stress. Such kind of circumstances may be handled with supplementation of antioxidants A-Z syrup with their regular treatment. &nbsp

ATTENUATION OF IRON OVERLOAD AND EFFECT OF ANTIOXIDANTS SUPPLEMENTATION ON OXIDATIVE STRESS IN HOMOZYGOUS β-THALASSEMIA

It has been projected that ferritin and iron yoke in homozygous thalassemic children is coupled with the enhanced free radical formation and blemished in antioxidative defense coordination. Aim: The purpose of the current study was to analyze the consequence of serum iron, erythrocyte catalase, and erythrocyte superoxide dismutase (ESOD) in patients with beta-thalassemia major. Method: 60 beta-thalassemia major patients were studied before and after supplementation of A – Z antioxidants for 20 weeks, and status were compared with 60 age and sex-matched healthy normal.    Serum Iron estimation was carried out by Ramsay’s Dipyridyl Method. Estimation of erythrocyte superoxide dismutase was done by Kajari Das Method. The levels of Catalase concentration in erythrocytes were analyzed by the Goth method.  All the objectives mentioned above were run by using a UV visible Spectrophotometer (Systronix). Results: A marked enhancement was seen in the intensity of serum iron, and superoxide dismutase (p<0.001) with parallel decline was observed in the level of erythrocyte catalase (p<0.001) in homozygous thalassemia patients when compared with healthy subjects. After 20 weeks of regular supplementation of antioxidants A-Z syrup, which consists of multimineral multivitamins, the concentration of catalase was increased whereas iron and ESOD (p<0.001) were reduced significantly when compared with normal and baselines thalassemic patients. Conclusion: Due to multiple blood transfusions, beta-thalassemia major children are at advanced risk due to secondary iron surplus and intense oxidative stress. Such kind of circumstances may be handled with supplementation of antioxidants A-Z syrup with their regular treatment. &nbsp

ALTERATION IN SERUM ZINC AND COPPER CONCENTRATIONS AND EFFECT OF ORAL THERAPEUTIC SUPPLEMENTATION OF ZINC ON TRANSFUSION DEPENDANT BETA THALASSEMIA MAJOR PATIENTS

Zinc is one of the essential micronutrients in human and act as a cofactor for more than 300 enzymes and plays an essential role in human growth and development. It has been observed that there was low serum zinc and elevated  copper level in β-thalassemia major compared with normal. Zinc deficiency is considered one of the main factors contributing to growth, cardiovascular diseases, and puberty disorders in β-thalassemic patients. Aim: The goal of the study was to scrutinize the impact of serum zinc and copper concentration in patients with beta-thalassemia major and also to observe the effect of zinc supplementation on transfusion dependent beta-thalassemia patients for six months. Method: 52 beta-thalassemia major patients were studied before and after supplementation of zinc for six months, and status was compared with 52 age and sex-matched healthy normal.  Serum zinc and copper concentration were measured by atomic absorption spectrophotometry (AAS) method. Result: There was a significant depleted activity of  serum zinc level (p<0.001), and the copper level was increased significantly (p<0.001) in patients when compared with normal. After six months of supplementation of zinc, there was a significantly enhanced zinc concentration (p<0.001),and copper was marginally increased (p>0.05) when compared with normal and baselines. Conclusion: Beta Thalassemia  major children are on numerous blood transfusions all the way through their life. Due  to this  thalassemic children are at risk of secondary iron burden. This further leads to the  enhanced  oxidative stress. One of the way to may overcome this situation to supply regular zinc supplementation along with treatment, which may be helpful to manage the situation. &nbsp

Dysfunctional stem and progenitor cells impair fracture healing with age

Successful fracture healing requires the simultaneous regeneration of both the bone and vasculature; mesenchymal stem cells (MSCs) are directed to replace the bone tissue, while endothelial progenitor cells (EPCs) form the new vasculature that supplies blood to the fracture site. In the elderly, the healing process is slowed, partly due to decreased regenerative function of these stem and progenitor cells. MSCs from older individuals are impaired with regard to cell number, proliferative capacity, ability to migrate, and osteochondrogenic differentiation potential. The proliferation, migration and function of EPCs are also compromised with advanced age. Although the reasons for cellular dysfunction with age are complex and multidimensional, reduced expression of growth factors, accumulation of oxidative damage from reactive oxygen species, and altered signaling of the Sirtuin-1 pathway are contributing factors to aging at the cellular level of both MSCs and EPCs. Because of these geriatric-specific issues, effective treatment for fracture repair may require new therapeutic techniques to restore cellular function. Some suggested directions for potential treatments include cellular therapies, pharmacological agents, treatments targeting age-related molecular mechanisms, and physical therapeutics. Advanced age is the primary risk factor for a fracture, due to the low bone mass and inferior bone quality associated with aging; a better understanding of the dysfunctional behavior of the aging cell will provide a foundation for new treatments to decrease healing time and reduce the development of complications during the extended recovery from fracture healing in the elderly

Creating Structured Hydrogel Microenvironments for Regulating Stem Cell Differentiation

The development of distinct biomimetic microenvironments for regulating stem cell behavior and bioengineering human tissues and disease models requires a solid understanding of cell–substrate interactions, adhesion, and its role in directing cell behavior, and other physico-chemical cues that drive cell behavior. In the past decade, innovative developments in chemistry, materials science, microfabrication, and associated technologies have given us the ability to manipulate the stem cell microenvironment with greater precision and, further, to monitor effector impacts on stem cells, both spatially and temporally. The influence of biomaterials and the 3D microenvironment’s physical and biochemical properties on mesenchymal stem cell proliferation, differentiation, and matrix production are the focus of this review chapter. Mechanisms and materials, principally hydrogel and hydrogel composites for bone and cartilage repair that create “cell-supportive” and “instructive” biomaterials, are emphasized. We begin by providing an overview of stem cells, their unique properties, and their challenges in regenerative medicine. An overview of current fabrication strategies for creating instructive substrates is then reviewed with a focused discussion of selected fabrication methods with an emphasis on bioprinting as a critical tool in creating novel stem cell-based biomaterials. We conclude with a critical assessment of the current state of the field and offer our view on the promises and potential pitfalls of the approaches discussed

Anisotropic Properties of Articular Cartilage in an Accelerated In Vitro Wear Test

Many material properties of articular cartilage are anisotropic, particularly in the superficial zone where collagen fibers have a preferential direction. However, the anisotropy of cartilage wear had not been previously investigated. The objective of this study was to evaluate the anisotropy of cartilage material behavior in an in vitro wear test. The wear and coefficient of friction of bovine condylar cartilage were measured with loading in directions parallel (longitudinal) and orthogonal (transverse) to the collagen fiber orientation at the articular surface. An accelerated cartilage wear test was performed against a T316 stainless-steel plate in a solution of phosphate buffered saline with protease inhibitors. A constant load of 160 N was maintained for 14000 cycles of reciprocal sliding motion at 4 mm/s velocity and a travel distance of 18 mm in each direction. The contact pressure during the wear test was approximately 2 MPa, which is in the range of that reported in the human knee and hip joint. Wear was measured by biochemically quantifying the glycosaminoglycans (GAGs) and collagen that was released from the tissue during the wear test. Collagen damage was evaluated with collagen hybridizing peptide (CHP), while visualization of the tissue composition after the wear test was provided with histologic analysis. Results demonstrated that wear in the transverse direction released about twice as many GAGs than in the longitudinal direction, but that no significant differences were seen in the amount of collagen released from the specimens. Specimens worn in the transverse direction had a higher intensity of CHP stain than those worn in the longitudinal direction, suggesting more collagen damage from wear in the transverse direction. No anisotropy in friction was detected at any point in the wear test. Histologic and CHP images demonstrate that the GAG loss and collagen damage extended through much of the depth of the cartilage tissue, particularly for wear in the transverse direction. These results highlight distinct differences between cartilage wear and the wear of traditional engineering materials, and suggest that further study on cartilage wear is warranted. A potential clinical implication of these results is that orienting osteochondral grafts such that the direction of wear is aligned with the primary fiber direction at the articular surface may optimize the life of the graft

Therapeutic Applications of Halloysite

In recent years, nanomaterials have attracted significant research interest for applications in biomedicine. Many kinds of engineered nanomaterials, such as lipid nanoparticles, polymeric nanoparticles, porous nanomaterials, silica, and clay nanoparticles, have been investigated for use in drug delivery systems, regenerative medicine, and scaffolds for tissue engineering. Some of the most attractive nanoparticles for biomedical applications are nanoclays. According to their mineralogical composition, approximately 30 different nanoclays exist, and the more commonly used clays are bentonite, halloysite, kaolinite, laponite, and montmorillonite. For millennia, clay minerals have been extensively investigated for use in antidiarrhea solutions, anti-inflammatory agents, blood purification, reducing infections, and healing of stomach ulcers. This widespread use is due to their high porosity, surface properties, large surface area, excellent biocompatibility, the potential for sustained drug release, thermal and chemical stability. We begin this review by discussing the major nanoclay types and their application in biomedicine, focusing on current research areas for halloysite in biomedicine. Finally, recent trends and future directions in HNT research for biomedical application are explored

Novel Microfluidic Colon with an Extracellular Matrix Membrane

Collagen is a key element of basal lamina in physiological systems that participates in cell and tissue culture. Its function is for cell maintenance and growth, angiogenesis, disease progression, and immunology. The goal of our present study was to integrate a micrometer resolution membrane that is synthesized out of rat-tail type I collagen in a microfluidic device with apical and basolateral chambers. The collagen membrane was generated by lyophilization. In order to evaluate the compatibility of the resulting membrane with organs-on-chips technology, it was sandwiched between layers of polydimethylsiloxane (PDMS) that had been prepared by replica molding, and the device was used to culture human colon caco 2 cells on the top of the membrane. Membrane microstructure, transport, and cell viability in the organs-on-chips were observed to confirm the suitability of our resulting membrane. Through transport studies, we compared diffusion of two different membranes: Transwell and our resulting collagen membrane. We found that mass transport of 40 kDa dextran was an order of magnitude higher through the collagen membrane than that through the Transwell membrane. Human colon caco 2 cells were cultured in devices with no, Transwell, or ECM membrane to evaluate the compatibility of cells on the ECM membrane compared to the other two membranes. We found that caco 2 cells cultured on the collagen membrane had excellent viability and function for extended periods of time compared to the other two devices. Our results indicate a substantial improvement in establishing a physiological microenvironment for in vitro organs-on-chips

Performance evaluation of nanoclay enriched anti-microbial hydrogels for biomedical applications

A major factor contributing to the failure of orthopedic and orthodontic implants is post-surgical infection. Coating metallic implant surfaces with anti-microbial agents has shown promise but does not always prevent the formation of bacterial biofilms. Furthermore, breakdown of these coatings within the human body can cause release of the anti-microbial drugs in an uncontrolled or unpredictable fashion. In this study, we used a calcium alginate and calcium phosphate cement (CPC) hydrogel composite as the base material and enriched these hydrogels with the anti-microbial drug, gentamicin sulfate, loaded within a halloysite nanotubes (HNTs). Our results demonstrate a sustained and extended release of gentamicin from hydrogels enriched with the gentamicin-loaded HNTs. When tested against the gram-negative bacteria, the hydrogel/nanoclay composites showed a pronounced zone of inhibition suggesting that anti-microbial doped nanoclay enriched hydrogels can prevent the growth of bacteria. The release of gentamicin sulfate for a period of five days from the nanoclay-enriched hydrogels would supply anti-microbial agents in a sustained and controlled manner and assist in preventing microbial growth and biofilm formation on the titanium implant surface. A pilot study, using mouse osteoblasts, confirmed that the nanoclay enriched surfaces are also cell supportive as osteoblasts readily, proliferated and produced a type I collagen and proteoglycan matrix