Browsing by Author "Nair, MB"

Now showing 1 - 9 of 9
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    Adult Stem Cells on Methacrylic Acid Grafted Cocoon Silky Fibrous Scaffolds
    (Trends in Biomaterials & Artificial Organs., 2010) Mani, S; Nair, MB; Nisha, S; Sreenivasan, K; Jacob, M; John, A
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    Biodegradation and cytocompatibility studies of a triphasic ceramic coated porous hydroxyapatite for bone substitute applications
    (International Journal of Applied Ceramic Technology, 2008) John, A; Nair, MB; Varma, HK; Bernhardt, A; Gelinsky, M
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    Biodegradation and cytocompatibility studies of a triphasic ceramic-coated porous hydroxyapatite for bone substitute applications
    (INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, 2008) John, A; Nair, MB; Varma, HK; Bernhardt, A; Gelinsky, M
    Bone defects due to trauma or disease have led to the need for biomaterials as substitutes for tissue regeneration and repair. Herein, we introduce a porous triphasic ceramic-coated hydroxyapatite scaffold (HASi) for such applications. Interestingly, in the degradation experiments with isotonic buffer, HASi showed a significant release of silica with the disappearance of the tricalcium phosphate phase. Furthermore, the material also exhibited cytocompatibility with cultured bone marrow-derived mesenchymal stem cells of human origin. The material chemistry, together with the favorable cellular characteristics, indicates HASi as a promising candidate for critical-size bony defects, which still remains a formidable clinical challenge in the orthopedic scenario.
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    Bonnet monkey model for pancreatic changes in induced malnutrition
    (PANCREAS, 1999)
    Pancreatic degenerative lesions of identical nature could be induced in bonnet monkeys (Macaca radiata) fed protein-deficient tapioca or cassava starch-based and corn-starch-based diets for 3 or 5 months. Marked to severe lobular and acinar cell atrophy in animals fed low-protein diets resembled human pancreatic atrophy resulting from protein deficiency. Animals fed low-protein, high-carbohydrate diets showed lesions akin to tropical chronic calculus pancreatopathy with diabetes mellitus. The pancreatic lesions comprised moderate to marked acinar cell atrophy, marked islet hyperplasia or nesidioblastosis with hypertrophy and mucoid metaplasia of the duct epithelium. Mucoid vasculopathy of the pancreatic artery and arterioles was observed in all animals given protein-deficient diets. It was enhanced in those given additional carbohydrate. Identical lesions were observed after using either source of carbohydrate. This excluded the role of toxic factors such as cyanoglycosides or heavy metals from a tapioca source in initiating the lesions. The study establishes monkey models for the spectrum of human pancreatic changes associated with malnutrition owing to protein deficiency and nutritional imbalance with low-protein high-starch diets. The experiments demonstrate the dual effects of similar diets on the parenchyma and vasculature of the pancreas.
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    Cell interaction studies with novel Bioglass coated Hydroxyapatite porous blocks
    (Trends in Biomaterials & Artificial Organs., 2006) Nair, MB; Varma, HK; Kumary, TV; Babu, SS; John, A
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    Evaluation of Biomaterials Using Micro-Computerized Tomography
    (CT 2008: TOMOGRAPHY CONFLUENCE, 2008) Arun, TAT; Soumya, CKC; Saaj, US; Nair, MB; Kalliyana, KV
    Micro-computed tomography or Micro-CT is a high resolution, non-invasive, x-ray scanning technique that allows precise three-dimensional imaging and quantification of micro-architectural and structural parameters of objects. Tomographic reconstruction is based on a cone-beam convolution-back-projection algorithm. Micro-architectural and structural parameters such as porosity, Surface area to volume ratio, interconnectivity, pore size, wall thickness, anisotropy and cross-section area of biomaterials and bio-specimens such as trabecular bone, polymer scaffold, bio-ceramics and dental restorative were evaluated through imaging and computer aided manipulation of the object scan data sets.
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    Tissue-engineered triphasic ceramic coated hydroxyapatite induced bone formation and vascularization at an extraskeletal site in a rat model
    (BULLETIN OF MATERIALS SCIENCE, 2011) Nair, MB; Varma, HK; Mohanan, PV; John, A
    Tissue-engineered bone regeneration has attracted much attention because of its high clinical demand for restoration of injured tissues. In the present study, we have evaluated the capability of bare (without cells) and tissue-engineered (with osteogenic-induced rat Mesenchymal Stem Cells (MSCs)) bioactive ceramics such as hydroxyapatite (HA) and triphasic ceramic-coated hydroxyapatite (HASi) to mediate vascularisation and osteoinduction at an extraskeletal site of rat model. The viability, proliferation and osteogenic differentiation of MSCs on the scaffolds were assessed in vitro and thereby established the capability of HASi in providing a better structural habitat than HA. The vascular invasion was relatively low in bare and tissue-engineered HA at 2 and 4 weeks. Interestingly, the implantation site was well vascularised with profuse ingrowth of blood capillaries in HASi groups, with preference for tissue-engineered HASi groups. Similarly, neo-osteogenesis studies were shown only by tissue-engineered HASi groups. The ingrowth of numerous osteoblast-like cells was seen around and within the pores of the material in bare HASi and tissue-engineered HASi groups (very low cellular infiltration in bare HA groups), but there was no osteoid deposition. The positive impact in forming bone in tissue-engineered HASi groups is attributable to the scaffold and to the cells, with the first choice for scaffold because both HA and HASi were engineered simultaneously with the cells from same source and same passage. Thus, highly porous interconnected porous structure and appropriate chemistry provided by HASi in combination with osteogenic-induced MSCs facilitated better vascularisation that lead to neo-osteogenesis.
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    Triphasic ceramic coated hydroxyapatite as a niche for goat stem cell-derived osteoblasts for bone regeneration and repair
    (JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE, 2009) Nair, MB; Varma, HK; John, A
    Current treatment strategies for the repair or replacement of bone use synthetic implants with stem cells and their progeny--a new approach to address unmet medical needs. This study has evaluated the effect of a silica-coated bioactive ceramic, namely HASi in comparison to hydroxyapatite (HA) on the adhesion, proliferation and osteogenic differentiation of goat bone marrow-derived mesenchymal stem cells in vitro in a prolonged culture of 28 days. The cellular activities were significantly enhanced on HASi signifying the role of silica to stimulate osteoblast cells. The fabrication of such a 'cell-ceramic construct using autologous MSCs' is aimed for the transplantation to a large bone defect site in the goat femur model which still remains a formidable challenge in Orthopedic surgery.