Urinary bladder matrix does not improve tenogenesis in an in vitro equine model.

The research article explores the effects of using Urinary Bladder Matrix (UBM) to improve healing and growth in tendon cells, utilizing an in vitro equine model. However, the results indicate that UBM doesn’t substantially improve tenogenesis or matrix organization beyond what the original tendon extracellular matrix (ECM) achieves alone.

Research Objectives and Hypothesis

• The main objective of this study was to investigate the ability of UBM, specifically derived from swine, to induce stronger organization within the tendon’s extracellular matrix and prompt tenogenesis – the creation of new tendon cells. All this was done using an innovative laboratory (in vitro) model.
• The researchers hypothesized that introducing UBM to tendon ECM in hydrogels would lead to better matrix organization and enhanced cell differentiation compared to a control group.

Methodology

• To test this hypothesis, hydrogels seeded with bone marrow cells originating from adult horses were shaped using rat tail tendon ECM. Some were treated with UBM, while others were not (control group).
• The researchers maintained these constructs in a state of static tension and evaluated them at two time points: 7 days and 21 days.
• The aspects studied were: how much the constructs contracted, cell viability, histology (microscopic structure of the tissues), biochemistry (chemical processes within the tissues), and gene expression (activity level of genes).

Results

• The results showed that by day 7, UBM-treated constructs contracted significantly from their original size, unlike the control group.
• By day 21, both UBM-treated and control constructs had undergone significant contraction.
• In both cases, the cells remained viably active over time and morphed from a rounded, random arrangement to an elongated configuration along the tension lines. The ECM also visibly compacted over time.
• However, when it came to aspects like nuclear aspect ratio, DNA, or glycosaminoglycan content, there were no changes over time or between treatments.
• Certain genes like Decorin, MMP-13, and Scleraxis exhibited a marked increase in expression over time, but UBM treatment didn’t affect this trend. The expression of Mohawk remained constant, and COMP diminished over time in both groups.

Conclusion

• The researchers ultimately concluded that while substantial matrix organization and cell differentiation took place in the novel ECM hydrogel model, adding UBM did not generate greater matrix organization than what the tendon ECM achieved independently.