The Effect of Gradations in Mineral Content, Matrix Alignment, and Applied Strain on Human Mesenchymal Stem Cell Morphology within Collagen Biomaterials

Abstract

The tendon-bone junction (TBJ) is a unique, mechanically dynamic, structurally graded anatomical zone which transmits tensile loads between tendon and bone. Current surgical repair techniques rely on mechanical fixation and can result in high re-failure rates. We have recently described a new class of collagen biomaterial that contains discrete mineralized and structurally aligned regions linked by a continuous interface to mimic the graded osteotendinous insertion. Here we report the combined influence of graded biomaterial environment and increasing levels of applied strain (0 – 20%) on MSC orientation and alignment. In osteotendinous scaffolds, which contain opposing gradients of mineral content and structural alignment characteristic of the native osteotendinous interface, MSC nuclear and actin alignment was initially dictated by the local pore architecture, while applied tensile strain enhanced cell alignment in the direction of strain. Comparatively, in layered scaffolds that did not contain any structural alignment cues, MSCs were randomly oriented in the unstrained condition, then became oriented in a direction perpendicular to applied strain. These findings provide an initial understanding of how scaffold architecture can provide significant, potentially competitive, feedback influencing MSC orientation under applied strain, and forms the basis for future tissue engineering efforts to regenerate the osteotendinous enthesis.

Piezo type mechanosensitive ion channel component 1 functions as a regulator of the cell fate determination of mesenchymal stem cells

“…The self-renewal and cell fate decisions of MSCs are extremely sensitive to changes in the extracellular environment and related factors, including extracellular matrix stiffness 4 , cell culture medium 5 , O 2 concentration 6 , three-dimensional scaffolds 7 , and mechanical stress. In particular, mechanical stress constitutes an essential factor for bone homeostasis and osteogenesis in skeletal tissue.…”

Evaluation of the Bone-ligament and tendon insertions based on Raman spectrum and its PCA and CLS analysis

“…To date, more and more researchers focus on this area to try to identify the mechanical and physiological functions and compose the biomaterials to mimic the nature structure of insertion 15 . Some researches use osteotendinous scaffolds, which contain opposing gradients of mineral content to mimic the nature insertion 16 .…”

Continuous two-phase in vitro co-culture model of the enthesis

“…In vivo models have been crucial in providing insight into enthesis development pathways [10,11], but a limited number of in vitro models have been developed [12–14]. Driven by the high occurrence of reconstruction surgeries for ligament and tendon tissues, there has been increased interest in providing bi- and tri-phasic scaffolds as alternative grafts, including differentiating mesenchymal stem cells into two lineages within the same scaffold [13,15–18]. A 2D zonal co-culture model between bone fibroblasts and osteoblasts with an overlapping interface has been proposed [14], but it is widely accepted that 3D scaffolds provide a more physiological microenvironment for cells [19].…”