Urinary Bladder Matrix Does Not Improve Tenogenesis in an In Vitro Equine Model.

The research conducted attempts to explore the impact of porcine urinary bladder matrix (UBM) on the improvement of tissue healing, particularly in tendons. However, the studies found that while there were some changes over time in terms of cell viability, shape, and matrix compaction, the addition of UBM did not lead to enhanced matrix organization or cell differentiation compared to the use of tendon ECM alone.

Study Design and Methodology

• The aim of the investigation was to inspect whether adding UBM to tendon ECM hydrogels leads to better matrix organization and cell differentiation.
• The experiment involved the use of hydrogels that were injected with bone marrow cells, obtained from six adult horses. These hydrogels were cast using tendon ECM from rat tails, both with and without the addition of UBM.
• The constructs were then held under static tension, with assessments taking place at 7 day and 21 day intervals. These assessments checked for factors such as construct contraction, cell viability, histology, biochemistry, and gene expression.

Key Findings

• The study observed that by Day 7, the UBM constructs had significantly contracted from their baseline measurements, even though the control constructs had not yet displayed any similar behavior.
• The study reports that by Day 21, both the control and UBM constructs had significantly contracted.
• All cells in both groups remained viable over the experimental time interval, and changed in shape from round to elongated, aligning along lines of tension. During this time, compaction of the ECM was visible.
• There was no observed difference, over time or between the treatments, in the nuclear aspect ratio, DNA, or glycosaminoglycan content.
• The levels of decorin, matrix metalloproteinase 13, and scleraxis expression increased notably with time, although this increase was not as a result of UBM treatment.
• Mohawk expression remained constant over the duration of the study.
• The cartilage oligomeric matrix protein expression decreased over time in both the control and UBM groups.

Conclusion

• The study concluded that a substantial amount of matrix organization and cell differentiation does occur over time using the novel ECM hydrogel model. Despite this, the addition of UBM did not stimulate greater matrix organization or cell differentiation in comparison to the utilization of tendon ECM alone.