• Human adipose tissue-derived mesenchymal stem/stromal cells adhere to and inhibit the growth of Staphylococcus aureus and Pseudomonas aeruginosa.

      Wood, Chelsea R.; Al Dhahri, Douaa; Pickles, Neil; Sammons, Rachel L.; Worthington, Tony; Wright, Karina T.; Johnson, William Eustace Basil; Al-Delfi, Ibtesam R. T. (2018-10-23)
      We have cultured and phenotyped human adipose tissue-derived mesenchymal stem/stromal cells (AT MSCs) and inoculated these cultures with bacteria common to infected skin wounds, i.e. Staphylococcus aureus and Pseudomonas aeruginosa. Cell interactions were examined by scanning electron microscopy (SEM), whilst bacterial growth was measured by colony forming unit (c.f.u.) and biofilm assays. AT MSCs appeared to attach to the bacteria and to engulf S. aureus. Significantly fewer bacterial c.f.u. were present in AT MSC : bacterial co-cultures compared with bacteria cultured alone. Antibacterial activity, including an inhibition of P. aeruginosa biofilm formation, was observed when bacteria were treated with conditioned medium harvested from the AT MSC :  bacterial co-cultures, irrespective of the bacterial species to which the AT MSCs had been exposed to previously. Hence, we have demonstrated that AT MSCs inhibit the growth of two common bacterial species. This was associated with bacterial adhesion, potential engulfment or phagocytosis, and the secretion of antibacterial factors.
    • An In Vitro Comparison of the Incorporation, Growth, and Chondrogenic Potential of Human Bone Marrow versus Adipose Tissue Mesenchymal Stem Cells in Clinically Relevant Cell Scaffolds Used for Cartilage Repair

      Kohli, Nupur; Johnson, William Eustace Basil; Wright, Karina T.; Sammons, Rachel L.; Jeys, Lee; Snow, Martyn
      Aim: To compare the incorporation, growth, and chondrogenic potential of bone marrow (BM) and adipose tissue (AT) mesenchymal stem cells (MSCs) in scaffolds used for cartilage repair. Methods: Human BM and AT MSCs were isolated, culture expanded, and characterised using standard protocols, then seeded into 2 different scaffolds, Chondro-Gide or Alpha Chondro Shield. Cell adhesion, incorporation, and viable cell growth were assessed microscopically and following calcein AM/ethidium homodimer (Live/Dead) staining. Cell-seeded scaffolds were treated with chondrogenic inducers for 28 days. Extracellular matrix deposition and soluble glycosaminoglycan (GAG) release into the culture medium was measured at day 28 by histology/immunohistochemistry and dimethylmethylene blue assay, respectively. Results: A greater number of viable MSCs from either source adhered and incorporated into Chondro-Gide than into Alpha Chondro Shield. In both cell scaffolds, this incorporation represented less than 2% of the cells that were seeded. There was a marked proliferation of BM MSCs, but not AT MSCs, in Chondro-Gide. MSCs from both sources underwent chondrogenic differentiation following induction. However, cartilaginous extracellular matrix deposition was most marked in Chondro-Gide seeded with BM MSCs. Soluble GAG secretion increased in chondrogenic versus control conditions. There was no marked difference in GAG secretion by MSCs from either cell source. Conclusion: Chondro-Gide and Alpha Chondro Shield were permissive to the incorporation and chondrogenic differentiation of human BM and AT MSCs. Chondro-Gide seeded with BM MSCs demonstrated the greatest increase in MSC number and deposition of a cartilaginous tissue.