Biomedical subjects

A S Pandit

Publications and source records attributed to A S Pandit.

5 recordsLinked to original sources

PubMed2006

Reference models for mitral valve tissue engineering based on valve cell phenotype and extracellular matrix analysis.

The advance of mitral valve repair techniques through tissue engineering is impeded by the lack of information regarding the cellular and extracellular components of the mitral valve. The present study aims to expand our understanding of the mitral valve structure by analysing the synthesis of extracellular matrix (ECM) proteins and the expression of nitric oxide synthase (NOS). Valvular endothelial cells (VECs) and valvular interstitial cells (VICs) were isolated from porcine mitral valves. Immunochemical staining of ECM components, including type I, II, III, IV and V collagen, laminin, fibronectin, elastin and chondroitin sulphate (CS), was performed on both mitral valve tissue and cell cultures. Reverse transcription polymerase chain reaction and immunochemistry were used to analyse NOS expression in native valve and in culture. Both VECs and VICs synthesised the basement membrane components, laminin and type IV collagen both in vivo and in vitro, amongst other fibrous ECM proteins. Synthesis of type I collagen and CS was absent in VEC cultures. Each cell type had a characteristic profile of NOS expression. VECs synthesised endothelial NOS both in vivo and in vitro, with a minority of VICs expressing neuronal NOS in vitro. The present study reports newly recognised aspects of the mitral valve structure and the in vitro behaviour of mitral valve cell populations based on ECM synthesis and NOS expression. The presented profiles can be used as base tools for the generation of data necessary for the selection of ideal cell sources and for the design of appropriate scaffolds for the development of effective tissue-engineered mitral valves.

Actins↗

PubMed2000

Fibrin scaffold as an effective vehicle for the delivery of acidic fibroblast growth factor (FGF-1).

The effect of wound healing by fibrin and acidic fibroblast growth factor (FGF-1) in an in vivo model was evaluated in this study. Four full-thickness wounds were made on the dorsum of each rabbit (n = 5). Each of these wounds had different treatment groups: control, topical FGF-1 (100 microg/9 cm2), fibrin (2.0 mL at 60 mg/mL fibrinogen), and FGF-1 (100 microg/9 cm2)/fibrin. The animals were sacrificed at the end of 2 weeks. Histomorphometric analysis and mechanical testing were conducted to assess the healing response. FGF-1/fibrin treatment improved the mechanical properties of the healed tissue. Fibrin scaffold exhibited the desired tissue response, as demonstrated by the lack of inflammation, and was deemed an effective carrier for FGF-1.

Animals↗

PubMed1998

In vivo wound healing response to a modified degradable fibrin scaffold.

Pooled donor fibrin with an ultimate fibrinogen concentration of 60 mg/ml was used to study its effect on wound healing of surgically created ulcers in a rabbit ear. Water soluble polymer (PEG Mw = 20 KD) beads of 100-150 microns were added (12% by volume) to the fibrinogen to obtain a porous and rough structure. Five 6 mm-diameter ulcers to the depth of bare cartilage were created on each rabbit ear. There were two periods of study (4 and 8 days), with 15 ulcers in each time period, 5 of which were treated with a modified fibrin scaffold, 5 with a non-modified fibrin scaffold, and 5 served as control ulcers. The ulcer sites were subjected to routine histological processing and histomorphometrical quantification. Data analysis revealed significant increases in volume fraction of fibroblast and number of blood vessels in the modified fibrin scaffold treated ulcers over control and non-modified fibrin scaffold treated groups.

Animals↗

PubMed1998

Stimulation of angiogenesis by FGF-1 delivered through a modified fibrin scaffold.

A few studies have indicated that repeated dosing of acidic fibroblast growth factor (FGF-1) is essential to be effective in modulating the wound-healing response. However, little investigation has been done to determine the effective dosing regimen of FGF-1 or the appropriate carrier vehicle for this growth factor. The main objective of this study was to determine the effective angiogenic stimulatatory dose of FGF-1 delivered through a modified fibrin matrix, using a rabbit ear ulcer model. Specifically, the aim was to test the effects of FGF-1 on the angiogenic, fibroblastic, and epithelial responses in a wound model. Five 6-mm diameter ulcers to the depth of bare cartilage were created on each rabbit ear. Four different combinations (0.8, 8, 80, and 800 micrograms/ml) of the growth factor were examined across two periods of study. Pooled modified fibrin was used to deliver the growth factor. Histomorphometrical quantification was conducted after routine histological processing of the ulcers sites. Data analysis indicated a strong correlation between concentration and the histomorphometric response. In general, the growth factor treatments affected the healing response and exhibited a dose-dependent behavior. The addition of FGF-1 led to an increase in the angiogenic and fibroblastic responses, as well as an increase in the epithelialization rate. The preferred dose of 8 micrograms initiated a high epithelialization rate, fibroblastic, and angiogenic responses, and was the lowest dose required to initiate these responses.

Animals↗

PubMedDate not supplied

Effect of oxygen treatment and dressing oxygen permeability on wound healing.

Although it has been shown that both the level of tissue oxygen and its gradient are critical factors in the healing process, optimal conditions for oxygen therapy have not been determined. In this study, both the oxygen level and oxygen gradient for a full-thickness defect were modified on the basis of preceding in vitro studies to determine the effect on the healing process. The goal of this study was to help determine the optimal clinical oxygen treatment protocol. Specifically, the healing of full-thickness defects in a rabbit model as determined by histomorphometric analyses (cell and tissue volume fraction, epithelialization, and contraction) under two types of dressings with or without oxygen treatment (70% O(2)) was investigated. One of the dressings was more oxygen permeable than the other. No significant differences were found in the histomorphometric response between the wounds covered with the oxygen-permeable and oxygen-impermeable dressings in the group without supplemental oxygen. Oxygen treatment, however, seemed to enhance the healing response significantly. According to the histomorphometric response, the wounds covered with the oxygen-impermeable dressings were significantly better than those with the oxygen-permeable dressing in the oxygen-treated group after 1 week, but the wounds covered by the oxygen-permeable dressings were better healed at 3 weeks. Therefore, oxygen-impermeable dressings may be useful only in the early stages of healing, before granulation tissue formation.

Journal Article↗