Biomedical subjects

Saadiq F El-Amin

Publications and source records attributed to Saadiq F El-Amin.

6 recordsLinked to original sources

PubMed2006

Human osteoblast cells: isolation, characterization, and growth on polymers for musculoskeletal tissue engineering.

We performed a detailed examination of the isolation, characterization, and growth of human osteoblast cells derived from trabecular bone. We further examined the morphology, phenotypic gene expression, mineralization,and growth of these human osteoblasts on polyester polymers used for musculoskeletal tissue engineering. Polylactic-co-glycolic acid [PLAGA (85:15, 50:50, 75:25)], and poly-lactic acid (L-PLA, D,L-PLA) were examined. The osteoblastic expression of key phenotypic markers osteocalcin, alkaline phosphatase, collagen, and bone sialoprotein at 4 and 8 weeks was examined. Reverse transcription-polymerase chain reaction studies revealed that trabecular-derived osteoblasts were positive for all markers evaluated with higher levels expressed over long-term culture. These cells also revealed mineralization and maturation as evidenced by energy dispersive X-ray analysis and scanning electron microscopy. Growth studies on PLAGA at 50:50,75:25, and 85:15 ratios and PLA in the L and DL isoforms revealed that human osteoblasts actively grew, with significantly higher cell numbers attached to scaffolds composed of PLAGA 50:50 in the short term and PLAGA 85:15 in the long term compared with PLA (p < 0.05). We believe human cell adhesion among these polymeric materials may be dependent on differences in cellular integrin expression and extracellular matrix protein elaboration.

Biocompatible Materials↗

PubMed2006

Bone graft substitutes.

The current gold standard of bone grafts is the autograft since it possesses all the characteristics necessary for new bone growth, namely osteoconductivity, osteogenicity and osteoinductivity. However, the autograft has its limitations, including donor-site morbidity and supply limitations, hindering this as an option for bone repair. An extensive list of currently available alternatives to bone grafts is provided, along with a classification scheme that divides these bone graft substitutes into five groups depending on the primary material composition: allograft, cell, factor, ceramic and polymer. Of the bone graft substitutes listed, several are discussed in detail. Beyond the current state of the art, attention is paid to what lies ahead in the field of bone graft substitutes. Biodegradable composite structures and various new architectures are discussed, as are newly developed polymeric materials, with tissue engineering providing the platform for future directions within this discipline.

Animals↗

PubMed2004

Molecular regulation of osteoblasts for tissue engineered bone repair.

The use of biodegradable polymers in medicine and biomedical research is increasing. A key growth area has been the use of these materials in tissue engineering, especially for guided regeneration of bone and cartilage. Our interest has been in determining the mechanisms by which cellular attachment and growth occurs on these materials. In the current study, we examined human osteoblast cell adhesion, growth, and morphologic changes on polymeric scaffolds composed of polylactic-co-glycolic acid and polylactic acid materials. We examined these characteristics in association with measurements of levels of key adhesion integrin receptors in the presence and absence of antibodies against alpha2, alpha3, alpha4, alpha5, alpha6, and beta1 subunits, and the adhesion ligand peptides RGD (Arg-Gly-Asp) and RGE (Arg-Gly-Ser). At 2 hours, results showed initial cell adhesion was considerably decreased on polylactic-co-glycolic acid and polylactic acid in the presence of the alpha2 and beta1, antibodies with a 70% adhesion rate difference observed among the groups evaluated. Higher levels of inhibition were observed on polylactic-co-glycolic acid relative to polylactic acid, which may be correlated to a higher number of cells being able to interact with the surface initially. The presence of known competitive peptide (RGD) at 2 hours, revealed its ability to block cellular adhesion to these matrices relative to the control and noncompetitive peptide RGE on polylactic-co-glycolic acid matrices. Overall adhesion rate was affected by the presence of the integrin antibodies to the alpha2, alpha3, alpha4, alpha5, alpha6, and beta1 subunits with highest differences among polylactic-co-glycolic acid relative to its control, therefore suggesting that initial osteoblastic cell adhesion to commonly used biomaterials is regulated through integrin binding.

Biocompatible Materials↗

PubMed2003

In vitro bone formation using muscle-derived cells: a new paradigm for bone tissue engineering using polymer-bone morphogenetic protein matrices.

Over 800,000 bone grafting procedures are performed in the United States annually, creating a demand for viable alternatives to autogenous bone, the grafting standard in osseous repair. The objective of this study was to examine the efficacy of a BMP-polymer matrix in inducing the expression of the osteoblastic phenotype and in vitro bone formation by muscle-derived cells. Specifically, we evaluated the ability of bone morphogenetic protein-7 (BMP-7), delivered from a poly(lactide-co-glycolide) (PLAGA) matrix, to induce the differentiation of cells derived from rabbit skeletal muscle into osteoblast-like cells and subsequently form mineralized tissue. Results confirmed that muscle-derived cells attached and proliferated on the PLAGA substrates. BMP-7 released from PLAGA induced the muscle-derived cells to increase bone marker expression and form mineralized cultures. These results demonstrate the efficacy of a BMP-polymer matrix in inducing the expression of the osteoblastic phenotype by muscle-derived cells and present a new paradigm for bone tissue engineering.

Absorbable Implants↗

PubMed2003

Three-dimensional, bioactive, biodegradable, polymer-bioactive glass composite scaffolds with improved mechanical properties support collagen synthesis and mineralization of human osteoblast-like cells in vitro.

In the past decade, tissue engineering-based bone grafting has emerged as a viable alternative to biological and synthetic grafts. The biomaterial component is a critical determinant of the ultimate success of the tissue-engineered graft. Because no single existing material possesses all the necessary properties required in an ideal bone graft, our approach has been to develop a three dimensional (3-D), porous composite of polylactide-co-glycolide (PLAGA) and 45S5 bioactive glass (BG) that is biodegradable, bioactive, and suitable as a scaffold for bone tissue engineering (PLAGA-BG composite). The objectives of this study were to examine the mechanical properties of a PLAGA-BG matrix, to evaluate the response of human osteoblast-like cells to the PLAGA-BG composite, and to evaluate the ability of the composite to form a surface calcium phosphate layer in vitro. Structural and mechanical properties of PLAGA-BG were measured, and the formation of a surface calcium phosphate layer was evaluated by surface analysis methods. The growth and differentiation of human osteoblast-like cells on PLAGA-BG were also examined. A hypothesis was that the combination of PLAGA with BG would result in a biocompatible and bioactive composite, capable of supporting osteoblast adhesion, growth and differentiation, with mechanical properties superior to PLAGA alone. The addition of bioactive glass granules to the PLAGA matrix resulted in a structure with higher compressive modulus than PLAGA alone. Moreover, the PLAGA-BA composite was found to be a bioactive material, as it formed surface calcium phosphate deposits in a simulated body fluid (SBF), and in the presence of cells and serum proteins. The composite supported osteoblast-like morphology, stained positively for alkaline phosphatase, and supported higher levels of Type I collagen synthesis than tissue culture polystyrene controls. We have successfully developed a degradable, porous, polymer bioactive glass composite possessing improved mechanical properties and osteointegrative potential compared to degradable polymers of poly(lactic acid-glycolic acid) alone. Future work will focus on the optimization of the composite scaffold for bone tissue-engineering applications and the evaluation of the 3-D composite in an in vivo model.

Biocompatible Materials↗

PubMed2002

Integrin expression by human osteoblasts cultured on degradable polymeric materials applicable for tissue engineered bone.

The use of biodegradable polymers in the field of orthopaedic surgery has gained increased popularity, as surgical pins and screws, and as potential biological scaffolds for repairing cartilage and bone defects. One such group of polymers that has gained considerable attention are the polyesters, poly(lactide-co-glycolide) (PLAGA) and polylactic acid (PLA), because of their minimal tissue inflammatory response, favorable biocompatibility and degradation characteristics. The objective of this study was to evaluate human osteoblastic cell adherence and growth on PLAGA and PLA scaffolds by examining integrin receptor (alpha2, alpha3, alpha4, alpha5, alpha6 and beta1) expression. Primary human osteoblastic cells isolated from trabecular bone adhered efficiently to both PLAGA and PLA, with the rate of adherence on PLAGA comparable to that of control tissue culture polystyrene (TCPS), and significantly higher than on PLA polymers at 3, 6 and 12 h. Human osteoblastic phenotypic expression, alkaline phosphatase (ALP) activity was positive on both degradable matrices, whereas osteocalcin levels were significantly higher on cells grown on PLAGA than on PLA composites. Interestingly, the integrin subunits, alpha2, alpha3, alpha4, alpha5, alpha6 and beta1 were all expressed at higher levels by osteoblasts cultured on PLAGA than those on PLA as analyzed by westerns blots and by flow cytometry. Among the integrins, alpha2, beta5 and beta1 showed the greatest difference in levels between the two surfaces. Thus, both PLA and PLAGA support osteoblastic adhesion and its accompanying engagement of integrin receptor and expression of osteocalcin and ALP. However PLAGA consistently appeared to be a better substrate for osteoblastic cells based on these parameters. This study is one of the first to investigate the ability of primary human osteoblastic cells isolated from trabecular bone to adhere to the biodegradable polymers PLAGA and PLA, and to examine the expression of their key adhesion receptors (integrins) on these substrates.

Absorbable Implants↗