Encapsulation of Equine Endothelial Colony Forming Cells in Highly Uniform, Injectable Hydrogel Microspheres for Local Cell Delivery.

The research examines how endothelial colony forming cells (ECFCs) stay viable and localize after being injected using an injectable hydrogel microsphere delivery method. The study specifically uses equine ECFCs and tests the technique’s effectiveness on wound healing in horses’ limbs.

Research Methodology

• The research was devised to solve a common problem in cell therapy: maintaining the viability and location of injected therapeutic cells. In many clinical applications, cells are directly injected, but this may result in lower survival and retention rates due to the mechanical stresses involved.
• To provide a solution, the researchers encapsulated ECFCs in a poly(ethylene glycol)-fibrinogen (PF) hydrogel microsphere. This process was facilitated by a specially designed microfluidic device which allows a high concentration of cells (10 million per milliliter) to be rapidly encapsulated.
• The encapsulated cells were placed inside uniformly shaped and sized microspheres to ensure the cell-laden objects were structurally consistent before injection.

Results of the Study

• Following encapsulation, the viability of the ECFCs was >95%, indicating high survival rates. The cells also continued to proliferate rapidly after encapsulation.
• The cells maintained their signature characteristics after encapsulation. This was demonstrated with markers (von Willebrand factor, CD105, and CD14), capability to form tubules on basement membrane matrix, and ability to process low-density lipoprotein. Their performance in these aspects posed no significant difference pre- and post-encapsulation.
• The viability of the cells remained steady even when passed through 18-23 gauge needles, thus proving their stability for injection.
• The applicability of this encapsulation method was tested in a real-world scenario. Autologous equine ECFCs were encapsulated and injected into the wound areas of adult horses’ limbs. The cells were labeled with fluorescent nanodots for visibility.
• One week post-injection, the analysis of biopsy samples from the wound edges showed that the encapsulated cells had migrated into the surrounding tissue. This demonstrates the method’s effectiveness in retaining the delivered cells and fostering their survival.

Conclusion

• In conclusion, the research illustrates the potential benefits of using PF microsphere encapsulation for cell delivery in large animal cell therapy. The method shows promise not only in terms of practicality and scalability, but also for clinical relevance with higher cell retention and survival rates.