Effect of Dynamic Culture and Periodic Compression on Human Mesenchymal Stem Cell Proliferation and Chondrogenesis

Abstract

We have recently developed a bioreactor that can apply both shear and compressive forces to engineered tissues in dynamic culture. In our system, alginate hydrogel beads with encapsulated human mesenchymal stem cells (hMSCs) were cultured under different dynamic conditions while subjected to periodic, compressive force. A customized pressure sensor was developed to track the pressure fluctuations when shear forces and compressive forces were applied. Compared to static culture, dynamic culture can maintain a higher cell population throughout the study. With the application of only shear stress, qRT-PCR and immunohistochemistry revealed that hMSCs experienced less chondrogenic differentiation than the static group. The second study showed that chondrogenic differentiation was enhanced by additional mechanical compression. After 14 days, alcian blue staining showed more extracellular matrix formed in the compression group. The upregulation of the positive chondrogenic markers such as Sox 9, aggrecan, and type II collagen were demonstrated by qPCR. Our bioreactor provides a novel approach to apply mechanical forces to engineered cartilage. Results suggest that a combination of dynamic culture with proper mechanical stimulation may promote efficient progenitor cell expansion in vitro, thereby allowing the culture of clinically relevant articular chondrocytes for the treatment of articular cartilage defects.

Osteochondral tissue coculture: An in vitro and in silico approach

“…Pazzano et al () also showed that the flow perfusion was able to maintain the pH gradient throughout the scaffold leading to increased DNA content. However, other researchers found that the flow perfusion led to downregulation of SOX9, GAG, and collagen II expressions, indicating reduced chondrogenic and increased osteogenic differentiation (Guo et al, ; Kock, Malda, Dhert, Ito, & Gawlitta, ; Mizuno, Allemann, & Glowacki, ). The discrepancy can be caused by the higher flow rate used in those studies (0.33, 1, and1.22 ml/min), which led to increased FSS on the cells.…”

A flow perfusion bioreactor with controlled mechanical stimulation: Application in cartilage tissue engineering and beyond

“…One study found hBMSCs encapsulated in alginate beads had 1.6 times more cells [49]. Others found hBMSCs secrete more GAGs in the dynamic environment of a TPB as evidenced by Alcian blue staining [51]. These advantages are likely due to the enhancement in mass transfer caused by perfusion through and around packed scaffolds, which also enhances shear stress.…”

Lung bioengineering: physical stimuli and stem/progenitor cell biology interplay towards biofabricating a functional organ

“…Indeed, physical stimuli have been shown to modulate stem cell differentiation. For instance, electrical stimuli in case of cells directed to the nervous, cardiac and muscular systems, or compression and extension in cells aimed to bioengineer tendons and bones [22–26]. …”