Influence of intermittent pressure, fluid flow, and mixing on the regenerative properties of articular chondrocytes.

The research article investigates how various physical stimuli affect the regenerative properties of young equine articular chondrocytes when cultured within a specific medium described as a polyglycolic acid nonwoven mesh.

Study Design

• The researchers developed a series of experiments in which young equine articular chondrocytes, embedded within a polyglycolic acid nonwoven mesh, were subjected to different conditions of intermittent pressure, fluid flow, and mixing to study their effects on neochondrogenesis.
• The cell/polymer constructs were first placed in 125 ml spinner flasks for different periods (1, 2 or 4 weeks) and then transferred to a perfusion system with intermittent pressure for a total of up to 6 weeks.
• Some constructs were subjected to the same conditions within the spinner flasks for the entire 6 weeks duration or for just 1 week before being moved to the perfusion system for 5 weeks, but without the inclusion of intermittent pressure.

Key Findings

• The study found that tissue constructs which were cultivated for 2 or 4 weeks in spinner flasks and then exposed to perfusion with intermittent pressure registered significantly higher concentrations of both sulfated glycosaminoglycan and collagen. These are markers indicating improved neochondrogenesis compared to constructs cultured entirely in spinners or those almost entirely subjected to the pressure/perfusion system.
• It was further observed that the initial stages of growth within the spinner flasks, with the inclusion of turbulent mixing, greatly enhanced both cell attachment and the early development of the extracellular matrix.
• Following this stage, further culture with perfusion and intermittent pressure appeared to accelerate matrix formation, contributing towards the cells’ regenerative properties.

Conclusion

• The compressive modulus was found to be directly proportional to the concentration of sulfated glycosaminoglycan in all physically-stressed constructs, with a stronger correlation observed in the pressurized examples.
• Constructs that weren’t subject to stress beyond the initial 1-week seeding period lost their mechanical integrity, implying that physical stimulation, particularly when intermittent pressure is applied, enhances the development and functional capacity of immature tissue constructs.

Implications

• The implications of this research could impact the field of tissue engineering and regenerative medicine, particularly in strategies aimed at promoting the neochondrogenesis of young cells.
• Further understanding of the contributions of different physical stimuli to the regenerative process could guide future efforts in creating optimal conditions for the cultivation of tissue constructs.