Macromolecular crowding in human tenocyte and skin fibroblast cultures: A comparative analysis.

Although human tenocytes and dermal fibroblasts have shown promise in tendon engineering, no tissue engineered medicine has been developed due to the prolonged ex vivo time required to develop an implantable device. Considering that macromolecular crowding has the potential to substantially accelerate the development of functional tissue facsimiles, herein we compared human tenocyte and dermal fibroblast behaviour under standard and macromolecular crowding conditions to inform future studies in tendon engineering. Basic cell function analysis made apparent the innocuousness of macromolecular crowding for both cell types. Gene expression analysis of the without macromolecular crowding groups revealed expression of tendon related molecules in human dermal fibroblasts and tenocytes. Protein electrophoresis and immunocytochemistry analyses showed significantly increased and similar deposition of collagen fibres by macromolecular crowding in the two cell types. Proteomics analysis demonstrated great similarities between human tenocyte and dermal fibroblast cultures, as well as the induction of haemostatic, anti-microbial and tissue-protective proteins by macromolecular crowding in both cell populations. Collectively, these data rationalise the use of either human dermal fibroblasts or tenocytes in combination with macromolecular crowding in tendon engineering.

Development of a dual-component infection-resistant arterial replacement for small-caliber reconstructions: A proof-of-concept study.

Introduction: Synthetic vascular grafts perform poorly in small-caliber (<6mm) anastomoses, due to intimal hyperplasia and thrombosis, whereas homografts are associated with limited availability and immunogenicity, and bioprostheses are prone to aneurysmal degeneration and calcification. Infection is another important limitation with vascular grafting. This study developed a dual-component graft for small-caliber reconstructions, comprising a decellularized tibial artery scaffold and an antibiotic-releasing, electrospun polycaprolactone (PCL)/polyethylene glycol (PEG) blend sleeve. Methods: The study investigated the effect of nucleases, as part of the decellularization technique, and two sterilization methods (peracetic acid and γ-irradiation), on the scaffold's biological and biomechanical integrity. It also investigated the effect of different PCL/PEG ratios on the antimicrobial, biological and biomechanical properties of the sleeves. Tibial arteries were decellularized using Triton X-100 and sodium-dodecyl-sulfate. Results: The scaffolds retained the general native histoarchitecture and biomechanics but were depleted of glycosaminoglycans. Sterilization with peracetic acid depleted collagen IV and produced ultrastructural changes in the collagen and elastic fibers. The two PCL/PEG ratios used (150:50 and 100:50) demonstrated differences in the structural, biomechanical and antimicrobial properties of the sleeves. Differences in the antimicrobial activity were also found between sleeves fabricated with antibiotics supplemented in the electrospinning solution, and sleeves soaked in antibiotics. Discussion: The study demonstrated the feasibility of fabricating a dual-component small-caliber graft, comprising a scaffold with sufficient biological and biomechanical functionality, and an electrospun PCL/PEG sleeve with tailored biomechanics and antibiotic release.

Preparation and Characterization of Tissue Surrogates Rich in Extracellular Matrix Using the Principles of Macromolecular Crowding.

Tissue engineering by self-assembly allows for the fabrication of living tissue surrogates by taking advantage of the cell's inherent ability to produce and deposit tissue-specific extracellular matrix. However, the long culture periods required to build a tissue substitute in conducive to phenotypic drift in vitro microenvironments result in phenotype and function losses. Although several biophysical microenvironmental modulators (e.g., surface topography, substrate stiffness, mechanical stimulation) have been used to address these issues, slow extracellular matrix deposition remains a limiting factor in clinical translation and commercialization of such therapies. Macromolecular crowding is an alternative in vitro microenvironment modulator that has been shown to accelerate extracellular matrix deposition by several orders of magnitude, thereby decreasing culture periods required for the development of an implantable device, while maintaining cell phenotype and function. Herein, we provide protocols for the production of tissue surrogates rich in extracellular matrix from human dermal fibroblasts, equine tenocytes, and equine adipose-derived stem cells using the principles of macromolecular crowding and the subsequent characterization thereof by means of immunofluorescent staining and complementary fluorescence intensity analysis.