Biswanath Kundu

The repair of segmental bone defects with porous bioglass: an experimental study in goat.

This study was exclusively conducted to evaluate healing of surgically created defects on the radius of adult Black Bengal goat after implantation of porous bioglass blocks and compare the process kinetics with normal healing. Twelve Black Bengal goats were divided randomly into two groups: control and experimental group implanted with bioglass blocks. Unicortical bone defects in radius were generated in all animals under aseptic condition. Local inflammatory reaction and healing of wound, radiological investigations, histological studies, oxytetracycline leveling and angiographic studies were performed up to 90th day post-operatively and compared with normal healing. It has been found that extensive new bone formation originating from host bone towards the implant whereas in control, the process was active from both the ends; the defect site appeared as homogenous nonfluorescent area. Thus, porous bioglass promoted bone formation over the entire extension of the defect independent of size of block in comparison to control group.

Development of New Localized Drug Delivery System Based on Ceftriaxone-Sulbactam Composite Drug Impregnated Porous Hydroxyapatite: A Systematic Approach for In Vitro and In Vivo Animal Trial

ABSTRACTPurposePresent investigation deals with an extensive approach incorporating in vitro and in vivo experimentation to treat chronic osteomyelitis, using hydroxyapatite porous scaffolds.Materials and MethodsHydroxyapatite was synthesized in the laboratory by wet chemical method, different porous scaffolds have been fabricated. In vitro studies include variation of porosity with interconnectivity, pore-drug interfacial studies by SEM-EDAX and drug elution studies (by HPLC) both in contact with PBS and SBF at ~37°C. In vivo trials were based on experimental osteomyelitis in rabbit model induced in tibia by Staphylococcus aureus. Characterizations included observation of histopathology, radiology and estimation of drug in both bone and serum for 42 days by HPLC method and subsequent bone-biomaterial interface by SEM.ResultsIt was established that lower pore percentage with a distribution of mainly micro-pores were found to be superior over the higher pore percentage both in vitro and in vivo. The criteria was matched with the 50N50H samples which had 50–55% porosity with an average pore size ~110 μm, having higher interconnectivity (10–100 μm), moderately high adsorption efficiency (~50%) when loaded with CFS (drug combinations consisting of irreversible b-lactamase inhibitor and b-lactam antibiotic). CFS release from HAp implants were faster in PBS than SBF. Further, both the results of in vitro and in vivo drug elution after 42 days showed release higher than minimum inhibitory concentration of CFS against Staphylococcus aureus. In vivo studies also proved the superiority of CFS loaded HAp implants than parenteral group based on eradication of infection and new bone formation.ConclusionsHAp based porous scaffold loaded with CFS and designed porosity (in terms of micro- and macro-porosity, interconnectivity) was found to be an ideal delivery system which could locally, sustainably release the composite antibiotic in reliable manner both in terms of in vitro drug elution behaviour in contact with SBF and in vivo animal trial.

Development of porous HAp and β-TCP scaffolds by starch consolidation with foaming method and drug-chitosan bilayered scaffold based drug delivery system

The inability to maintain high concentrations of antibiotic at the site of infection for an extended period of time along with dead space management is still the driving challenge in treatment of osteomyelitis. Porous bioactive ceramics such as hydroxyapatite (HAp) and beta-tri calcium phosphate (β-TCP) were some of the alternatives to be used as local drug delivery system. However, high porosity and high interconnectivity of pores in the scaffolds play a pivotal role in the drug release and bone resorption. Ceftriaxone is a cephalosporin that has lost its clinical popularity. But has recently been reported to exhibit better bactericidal activity in vitro and reduced probability of resistance development, in combination with sulbactam, a β-lactamase inhibitor. In this article, a novel approach of forming HAp and pure β-TCP based porous scaffolds by applying together starch consolidation with foaming method was used. For the purpose, pure HAp and β-TCP were prepared in the laboratory and after thorough characterization (including XRD, FTIR, particle size distribution, etc.) the powders were used for scaffold fabrication. The ability of these scaffolds to release drugs suitably for osteomyelitis was studied in vitro. The results of the study indicated that HAp exhibited better drug release profile than β-TCP when drug was used alone indicating the high influence of the carrier material. However, this restriction got relaxed when a bilayered scaffold was formed using chitosan along with the drug. SEM studies along with EDAX on the drug-chitosan bilayered scaffold showed closest apposition of this combination to the calcium phosphate surface.

Efficacy of nano-hydroxyapatite prepared by an aqueous solution combustion technique in healing bone defects of goat

The present study was undertaken to evaluate porous hydroxyapatite (HAp), the powder of which was prepared by a novel aqueous solution combustion technique, as a bone substitute in healing bone defects in vivo, as assessed by radiologic and histopathologic methods, oxytetracycline labeling, and angiogenic features in Bengal goat. Bone defects were created in the diaphysis of the radius and either not filled (group I) or filled with a HAp strut (group II). The radiologic study in group II showed the presence of unabsorbed implants which acted as a scaffold for new bone growth across the defect, and the quality of healing of the bone defect was almost indistinguishable from the control group, in which the defect was more or less similar, although the newly formed bony tissue was more organized when HAp was used. Histologic methods showed complete normal ossification with development of Haversian canals and well-defined osteoblasts at the periphery in group II, whereas the control group had moderate fibro-collagenization and an adequate amount of marrow material, fat cells, and blood vessels. An oxytetracycline labeling study showed moderate activity of new bone formation with crossing-over of new bone trabeculae along with the presence of resorption cavities in group II, whereas in the control group, the process of new bone formation was active from both ends and the defect site appeared as a homogenous non-fluoroscent area. Angiograms of the animals in the control group showed uniform angiogenesis in the defect site with establishment of trans-transplant angiogenesis, whereas in group II there was complete trans-transplant shunting of blood vessel communication. Porous HAp ceramic prepared by an aqueous combustion technique promoted bone formation over the defect, confirming their biologic osteoconductive property.

Fabrication and characterization of porous hydroxyapatite ocular implant followed by anin vivo study in dogs

Porous hydroxyapatite ocular implant was fabricated by a novel and simple method using hydroxyapatite powder synthesized in the laboratory. The porosity and pore size of the implant were controlled to make it light in weight as well as suitable for rapid vascularization after implantation. The implant was characterized by X-ray diffraction studies, infrared spectra and chemical analysis for phase purity and chemical composition. The pore morphology and pore size distribution of the samples were investigated by scanning electron microscope (SEM). Thereafter, efficacy of the implant was examined byin vivo study in dogs. Clinical, haematological and radiological studies indicated the suitability of the implant for replacement of the lost eye of human patients.

Protein growth factors loaded highly porous chitosan scaffold: a comparison of bone healing properties.

Present study aimed to investigate and compare effectiveness of porous chitosan alone and in combination with insulin like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) in bone healing. Highly porous (85±2%) with wide distribution of macroporous (70-900 μm) chitosan scaffolds were fabricated as bone substitutes by employing a simple liquid hardening method using 2% (w/v) chitosan suspension. IGF-1 and BMP-2 were infiltrated using vacuum infiltration with freeze drying method. Adsorption efficiency was found to be 87±2 and 90±2% for BMP-2 and IGF-1 respectively. After thorough material characterization (pore details, FTIR and SEM), samples were used for subsequent in vivo animal trial. Eighteen rabbit models were used to evaluate and compare control (chitosan) (group A), chitosan with IGF-1 (group B) and chitosan with BMP-2 (group C) in the repair of critical size bone defect in tibia. Radiologically, there was evidence of radiodensity in defect area from 60th day (initiated on 30th day) in groups B and C as compared to group A and attaining nearly bony density in most of the part at day 90. Histological results depicted well developed osteoblastic proliferation around haversian canal along with proliferating fibroblast, vascularization and reticular network which was more pronounced in group B followed by groups C and A. Fluorochrome labeling and SEM studies in all groups showed similar outcome. Hence, porous chitosan alone and in combination with growth factors (GFs) can be successfully used for bone defect healing with slight advantage of IGF-1 in chitosan samples.

Converted marine coral hydroxyapatite implants with growth factors: In vivo bone regeneration

Herein we report rabbit model in vivo bone regeneration of hydrothermally converted coralline hydroxyapatite (HCCHAp) scaffolds without (group I) and with growth factors namely insulin like growth factor-1 (IGF-1) (group II) and bone morphogenetic protein-2 (BMP-2) (group III). All HCCHAp scaffolds have been characterized for phase purity and morphology before implantation. Calcined marine coral was hydrothermally converted using a mineralizer/catalyst to phase pure HAp retaining original pore structure and geometry. After sintering at 1250°C, the HCCHAp found to have ~87% crystallinity, 70-75% porosity and 2±0.5MPa compressive strength. In vitro growth factor release study at day 28 revealed 77 and 98% release for IGF-1 and BMP-2, respectively. The IGF-1 release was more sustained than BMP-2. In vivo bone healing of different groups was compared using chronological radiology, histological evaluations, scanning electron microscopy and fluorochrome labeling up to 90days of implantation. In vivo studies showed substantial reduction in radiolucent zone and decreased radiodensity of implants in group II followed by group III and group I. These observations clearly suggest in-growth of osseous tissue, initiation of bone healing and complete union between implants and natural bone in group II implants. A statistical score sheet based on histological observations showed an excellent osseous tissue formation in group II and group III scaffolds and moderate bone regeneration in group I scaffolds.

Understanding osteomyelitis and its treatment through local drug delivery system

Chronic osteomyelitis is a major challenge in bone surgery. Conventional use of antibiotics is not an effective way to control the malaise due to so many reasons. Determination of optimal treatment strategy becomes difficult for the orthopaedic surgeons and as a consequence, the patients suffer not only from therapeutic failure but also due to adverse side effects of antibiotics and financial loss due to additional stay at hospitals. A wide application of carrier systems, as a medium for local delivery of antibiotics, is being used experimentally and clinically for the treatment of osteomyelitis. This kind of delivery system provides sustained higher concentration of antibiotics at the infection site with reduced possibility of toxicity. This review highlight etiology and pathophysiology of osteomyelitis, current therapeutic options with their limitations, and potentiality of biomaterial based carrier materials impregnated with antibiotics as local delivery approach.

Strategies for delivering bone morphogenetic protein for bone healing

Bone morphogenetic proteins (BMPs) are the most significant growth factors that belong to the Transforming Growth Factor Beta (TGF-β) super-family. Though more than twenty members of this family have been identified so far in humans, Food and Drug Administration (FDA) approved two growth factors: BMP-2 and BMP-7 for treatments of spinal fusion and long-bone fractures with collagen carriers. Currently BMPs are clinically used in spinal fusion, oral and maxillofacial surgery and also in the repair of long bone defects. The efficiency of BMPs depends a lot on the selection of suitable carriers. At present, different types of carrier materials are used: natural and synthetic polymers, calcium phosphate and ceramic-polymer composite materials. Number of research articles has been published on the minute intricacies of the loading process and release kinetics of BMPs. Despite the significant evidence of its potential for bone healing demonstrated in animal models, future clinical investigations are needed to define dose, scaffold and route of administration. The efficacy and application of BMPs in various levels with a proper carrier and dose is yet to be established. The present article collates various aspects of success and limitation and identifies the prospects and challenges associated with the use of BMPs in orthopaedic surgery.

Development and effect of different bioactive silicate glass scaffolds: In vitro evaluation for use as a bone drug delivery system

Local drug delivery systems to bone have attracted appreciable attention due to their efficacy to improve drug delivery, healing and regeneration. In this paper, development and characterization of new formulations of bioactive glass into a porous scaffold has been reported for its suitability to act as a drug delivery system in the management of bone infections, in vitro. Two new glass compositions based on SiO2-Na2O-ZnO-CaO-MgO-P2O5 system (BGZ and MBG) have been developed which after thorough chemical and phase evaluation, studied for acellular static in vitro bioactivity in SBF. Porous scaffolds made of these glasses have been fabricated and characterized thoroughly for bioactivity study, SEM, XRD, in vitro cytotoxicity, MTT assay and wound healing assay using human osteocarcoma cells. Finally, gatifloxacin was loaded into the porous scaffold by vacuum infiltration method and in vitro drug release kinetics have been studied with varying parameters including dissolution medium (PBS and SBF) and with/without impregnation chitosan. Suitable model has also been proposed for the kinetics. 63-66% porous and 5-50μm almost unimodal porous MBG and BGZ bioactive glass scaffolds were capable of releasing drugs successfully for 43 days at concentrations to treat orthopedic infections. In addition, it was also observed that the release of drug followed Peppas-Korsmeyer release pattern based on Fickian diffusion, while 0.5-1% chitosan coating on the scaffolds decreased the burst release and overall release of drug. The results also indicated that MBG based scaffolds were bioactive, biocompatible, noncytotoxic and exhibited excellent wound healing potential while BGZ was mildly cytotoxic with moderate wound healing potential. These results strongly suggest that MBG scaffolds appear to be a suitable bone drug delivery system in orthopedic infections treatment and as bone void fillers, but BGZ should be handled with caution or studied elaborately in detail further to ascertain and confirm the cytotoxic nature and wound healing potential of this glass.