Cyclic Tensile Strain Induces Tenogenic Differentiation of Tendon-Derived Stem Cells in Bioreactor Culture

Abstract

Different loading regimens of cyclic tensile strain impose different effects on cell proliferation and tenogenic differentiation of TDSCs in three-dimensional (3D) culture in vitro, which has been little reported in previous literatures. In this study we assessed the efficacy of TDSCs in a poly(L-lactide-co-ε-caprolactone)/collagen (P(LLA-CL)/Col) scaffold under mechanical stimulation in the custom-designed 3D tensile bioreactor, which revealed that cyclic tensile strain with different frequencies (0.3 Hz, 0.5 Hz, and 1.0 Hz) and amplitudes (2%, 4%, and 8%) had no influence on TDSC viability, while it had different effects on the proliferation and the expression of type I collagen, tenascin-C, tenomodulin, and scleraxis of TDSCs, which was most obvious at 0.5 Hz frequency with the same amplitude and at 4% amplitude with the same frequency. Moreover, signaling pathway from microarray analysis revealed that reduced extracellular matrix (ECM) receptor interaction signaling initiated the tendon genius switch. Cyclic tensile strain highly upregulated genes encoding regulators of NPM1 and COPS5 transcriptional activities as well as MYC related transcriptional factors, which contributed to cell proliferation and differentiation. In particular, the transcriptome analysis provided certain new insights on the molecular and signaling networks for TDSCs loaded in these conditions.

An in vitro investigation into the effects of 10 Hz cyclic loading on tenocyte metabolism

“…It is difficult to compare studies of different design to ascertain how loading frequency may influence cell response. However, the few studies which have directly investigated cell response to loading at more than one frequency suggest a more pronounced response with higher frequency loading, consistent with this current study . These studies demonstrated increased expression of type I and type III collagen, as observed in the current study, and also reported increased expressions of tenascin‐C, tenomodulin, and scleraxis.…”

“…Mechanical loading is one of the regulatory factors known to influence tendon metabolism, with tenocytes responsive to mechanical stimuli through mechanotransduction processes that regulate the expression of both anabolic and catabolic genes, and can lead to maintenance, remodeling, or degeneration of the tendon structure . Mechanotransduction studies generally adopt isolated cells to investigate cell response to varying strain conditions under more tightly controlled conditions, predominately investigating response to low‐frequency loading (0.3‐1 Hz) . However, previous studies have demonstrated that housing cells in a 3D environment can provide a more physiologically relevant cell environment as a basis for such investigations .…”

“…16,17 Mechanotransduction studies generally adopt isolated cells to investigate cell response to varying strain conditions under more tightly controlled conditions, predominately investigating response to low-frequency loading (0.3-1 Hz). 16,18,19 However, previous studies have demonstrated that housing cells in a 3D environment can provide a more physiologically relevant cell environment as a basis for such investigations. 20,21 For example, using 3D collagen gels, human Achilles tenocytes have been reported to express increases in ADAMTS2/4/16, MMP24, TIMP3, and type I collagen gene expression after 24-or 48-hours loading.…”

Transcriptome profiles of isolated murine Achilles tendon proper‐ and peritenon‐derived progenitor cells

“…If threshold cut-offs of p < 0.05 and fold change >2 are applied, then 741 genes were differentially expressed between the two regions considered (Table S- 8). Several of the markers previously used to describe tendon cells had greater expression in the tendon properderived progenitors, including Scx, Mkx, and Fmod ( Table 5).…”

“…Tendon proper stem/progenitor cells have been the focus of most tendon stem cells studies . Tendon proper progenitor cells have been shown to be affected by aging, by cues like inflammation leading to osteogenic differentiation, and to some extent by mechanical stimulation . In this study, we continue our focus on comparing both progenitor populations—those from the tendon proper and from the peritenon—in order to discern markers associated with each population.…”