Papers by Keyword: Collagen Type I

Abstract: Tissue engineering by self-assembly hypothesises that optimal repair and regeneration can be achieved best by using the cells’ inherent ability to create organs with proficiency still unmatched by currently available scaffold fabrication technologies. However, the prolonged culture time required to develop an implantable device jeopardises clinical translation and commercialisation of such techniques. Herein, we report that macromolecular crowding, a biophysical in vitro microenvironment modulator, dramatically accelerates extracellular matrix deposition in cultured human corneal, lung and dermal fibroblasts and human bone marrow mesenchymal stem cells. In fact, an almost 5 to 30 fold increase in collagen type I deposition was recorded as early as 48 hours in culture, without any negative effect in cell phenotype and function.

Abstract: The three dimensional scaffold of the bone marrow (BM) niches is composed of various elements including extracellular matrix proteins and cell types, such as collagen type I (Col I) and stroma cells. Interaction of stem cells with their microenvironment is important for their regulation. In the marrow, Col I is mostly localized in the endosteal regions. The objective of this work was to investigate the role of Col I in the regulation of Hematopoietic Stem Cells (HSC) and Mesenchymal Stem Cells (MSC) growth. Col I was extracted from rat tail tendons and its purity confirmed. Human BM MSCs and umbilical cord blood (UCB) CD34⁺ cells were used as Stem Cell sources. MSCs were cultured in medium with serum while CB CD34⁺ cells were cultured without serum with cytokines. The impact of increasing concentrations of Col I (0-50 µg mL^-1 for coating) on the growth of Hematopoietic Progenitor Cells (HPC) and MSCs was investigated by cytometry, microscopy and clonogenic progenitor assays. Only a minority of CD34⁺ cells expressed the Col I receptor α₂β₁ prior to culture, while the opposite was observed when hematopoietic cells were placed in culture. Col I coated surfaces reduced the expansion of hematopoietic cells by 25% compared to control, while expansions of myeloid and MK progenitors were either unchanged or negatively affected by Col I, respectively. The differentiation of HPCs was also affected on Col I as demonstrated by differences in the frequencies of various cell lineages, such as CD34⁺ cells, megakaryocytes (MK), erythrocytes and others. In contrast to HPCs, Col I surfaces increased MSCs proliferation but had little impact on osteoblasts derived from MSCs. Taken together, this study provides new insights into the regulatory activities of Col I on Stem Cells residing in the marrow.

Abstract: The object of this study was to investigate the effect of the concentration of orthosilicic acid (0, 0.5, 1, 5 and 10µM) on gene expression in human osteoblast cells isolated from trabecular bone. This was measured using reverse transcriptase-polymerase chain reaction (RT-PCR) to quantify messenger RNA (mRNA) levels for collagen type I, alkaline phosphatase and osteocalcin. Results showed that while collagen type I mRNA expression was increased by the addition of up to 10µM orthosilicic acid, ALP message was suppressed over time and osteocalcin levels were decreased.