Understanding the cell niche for tendon tissue engineering through physical scaffold cues

Abstract

Event Abstract Back to Event Understanding the cell niche for tendon tissue engineering through physical scaffold cues Brittany L. Banik1 and Justin L. Brown1 1 The Pennsylvania State University, Biomedical Engineering, United States Introduction: Tendons are fibrous tissues connecting muscles to bones and function to stabilize joints, transmit forces, and store and release energy. Current treatments for tendon repair—autografts, allograts, xenografts, and synthetic grafts—fall short from complete structure-function success in terms of biomechanics, biological integration, and cellular response. This project’s motivation is stimulated by rising incidences and related costs of tendon injuries, which are often painful and debilitating with poor healing capabilities. A significant tissue engineering component lies in understanding the cell microenvironment, or niche, and how to develop constructs that exploit the cellular responses to the niche. The major project objective is to examine physical cues of the biomaterial scaffold that affect cell signaling leading to proliferation and tenogenic differentiation. This project identifies fiber diameter as a scaffold variable that is a key cell niche component with potential to improve tendon graft design. High-throughput RT-PCR and signaling assays were utilized to probe the regulation of lineage specific genes and cell signaling changes. Materials and Methods: Electrospinning was used to synthesize polymer scaffolds. A 20 w/v (poly)ϵ-caprolactone (MW 70000–90000) 80:20, acetic acid:acetone, solution was used for scaffold fabrication. Fibers were spun onto 3D-printed grids for antibody array tests and RT-PCR. Voltage, flow rate, and target distance were kept constant at 15kV, 1.5mL/h, and 26 cm, respectively. For RT-PCR, human mesenchymal stem cells (MSCs) were cultured on ~500nm fibers for 7 days in basal growth media. Qiagen RT2 Profiler™ MSC PCR Array screened the expression of 89 genes. Results and Discussion: Fiber architecture and diameter are valuable considerations for bioinstructive geometries supporting tenogenic differentiation. Fig 1A illustrates the influence of fiber diameter as a scaffold feature. Previous data supports ~1um size fibers for osteogenic differentiation[1],[2], which warrants diameter investigation for tenogenesis. Fig 1B demonstrates fold changes in expression of genes corresponding to MSC development on fibers relative to flat control. Data in Fig 1B is striking in that the media is not supplemented and fibrous topography facilitated differentiation. These findings suggest fiber diameter is of interest to investigate as a key niche component for tendon regeneration. Conclusion: The results indicate the potential to use physical microenvironment cues to replace or augment growth factors via intracellular signaling pathways. Future considerations include testing fiber diameters and investigating cellular interactions on a 3D scaffold design. These results begin to provide a foundation in synthetic graft development to understand the cellular needs towards a more effective healing response. This material is based upon work supported by the National Science Foundation (NSF) under Grant No. DGE1255832. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF.