Biology subjects

Kafienah, W.

Publications and source records attributed to Kafienah, W..

4 recordsLinked to original sources

bioRxiv2020

Over-Confluence of expanded bone marrow mesenchymal stem cells ameliorates their chondrogenic capacity in 3D cartilage tissue engineering

Cartilage tissue engineering using bone marrow-derived mesenchymal stem cells (BM-MSCs) is a growing technology for the repair of joint defects. Culturing BM-MSCs to over confluence has historically been avoided due to perceived risk to cell viability, growth inhibition and differentiation potential. Here we show that a simple change in culture practice, based on mimicking the condensation phase during embryonic cartilage development, results in biochemically and histologically superior cartilage tissue engineered constructs. Whole transcriptome analysis of the condensing cells revealed a phenotype associated with early commitment to chondrogenic precursors. This simple adjustment to the common stem cell culture technique would impact the quality of all cartilage tissue engineering modalities utilising these cells.

cell biology↗

bioRxiv2020

Mechanisms of interaction of staphylococcus aureus with human mesenchymal stem cells and their differentiated phenotypes

Mesenchymal stem cells (MSCs) are multipotent cells commonly derived from the bone marrow, adipose tissue and placenta. Human bone marrow derived MSCs migrate to a site of injury, release proinflammatory cytokines and modulate T-cell proliferation. At sites of injury, MSCs may well encounter bacterial pathogens most commonly the Gram positive pathogen Staphylococcus aureus. However, the precise molecular mechanism(s) of this interaction remain to be elucidated. In the present study we aim to show if a direct interaction occurs between S. aureus and bone marrow derived MSCs and identify if MSCRAMMs have a role in this interaction. We further aim to compare S. aureus interaction with cells that differentiate from MSCs, namely; osteoblasts, adipocytes and chondrocytes, since MSCs co-exist in the niche of these cells. Our results showed that S. aureus is able to interact with MSCs in the form of adhesion and invasion to the cells, and that this interaction is largely dependent on the expression of fibronecting-binding protein (FnBP) by S. aureus. We also showed that the same mechanism of interaction to osteoblasts, adipocytes and chondrocytes that are directly differentiated from the same MSCs. Finally, we have found that the presence of 10% FBS in the infection medium is essential as it helps in achieving the best specific bacterial-cell association with the least background association. The results reveals a mechanism of interaction between S. aureus and MSCs that could pave the way for therapeutic intervention that minimises the burden of infection in inflammatory diseases.

microbiology↗

bioRxiv2018

Electrospun Cellulose-Silk Composite Nanofibres Direct Mesenchymal Stem Cell Chondrogenesis in the Absence of Biological Stimulation

Smart biomaterials with an inherent stimulating capacity that elicit specific behaviours in lieu of biological prompts would prove advantageous for regenerative medicine applications. Specific blends of the natural polymers cellulose and silk cast as films can drive the chondrogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs) upon in vitro culture. However, the true potential of such biomaterials for cartilage tissue engineering can be realised upon its three-dimensional fabrication. In this work we employ an electrospinning technique to model the in vivo nanofibrous extracellular matrix (ECM). Cellulose and silk polymers at a mass ratio of 75:25 were regenerated using a trifluoroacetic acid and acetic acid cosolvent system. This natural polymer composite was directly electrospun for the first time, into nanofibers without post-spun treatment. The presence and size of fibre beading was influenced by environmental humidity. The regenerated composite retained the key chemical functionalities of its respective components. Biocompatibility of the natural polymer composite with hMSCs was demonstrated and its inherent capacity to direct chondrogenic stem cell differentiation, in the absence of stimulating growth factors, was confirmed. This physical chondrogenic stimulation was countered biochemically using fibroblast growth factor-2 (FGF-2), a growth factor used to enhance the proliferation of hMSCs. The newly fabricated scaffold provides the foundation for designing a robust, self-inductive, and cost-effective biomimetic biomaterial for cartilage tissue engineering.

bioengineering↗

bioRxiv2018

Mesenchymal Stem Cell Chondroinduction on Cellulose-Silk Composites is Driven by Substrate Elasticity

Biomaterials that can physically control the fate of stem cells are critical for the application of in situ tissue engineering. However, the mechanisms underlying this phenomenon remain unclear. In this study, cellulose and silk composite substrates, known to induce physically the chondrogenic differentiation of human mesenchymal stem cells (MSCs), were regenerated to fabricate two-dimensional film surfaces. MSCs were grown on these surfaces in the presence of chemicals that interfere with the biochemical and mechanical signalling pathwys of MSCs. The data shows that preventing substrate surface elasticity transmission results in significant downregulation of chondrogenic gene expression. Interference with the classical, chondrogenic Smad2/3 Phosphorylation pathway does not impact the chondrogenic capacity of the substrates. The results highlight the importance of the substrate mechanical elasticity on chondrogenic MSCs and its independence of known chondrogenic biochemical pathways.

bioengineering↗