F. E. Ludwinski1, G. Damodaran1, A. S. Patel1, J. Cho1, S. Jayasinghe2, A. Smith1, B. Modarai1 1King’s College London School Of Medicine,School Of Cardiovascular And Medical Sciences,London, London, United Kingdom 2University College London,Department Of Mechanical Engineering,London, LONDON, United Kingdom
Introduction:
Cell therapy has been proposed as a means of improving perfusion of ischaemic limbs. Direct injection of pro-angiogenic cells has, however, shown only modest outcomes in clinical trials, perhaps because of their loss from the site of injection. Here, we investigate alginate microsphere encapsulation as a means of enhancing retention and improving reperfusion of the ischaemic hindlimb.
Methods:
150μm sodium alginate microspheres, containing 108cells/ml of Tie2-expressing murine bone marrow-derived macrophages (eTie2-iBMMs), were generated using a clinical-grade cell encapsulator. Comparisons were made between eTie2-iBMMs and non-encapsulated cells (nTie2-iBMMs), with respect to: cell viability and phenotype; in vitro pro-angiogenic function after angiopoietin-mediated stimulation of Tie2 (VEGF expression and endothelial tubule formation); cell retention (IVIS biofluorescent imaging); and ability to promote revascularisation in the ischaemic murine hindlimb.
Results:
Encapsulation did not affect Tie2-iBMM viability or phenotype up to 7days in vitro, the expression of VEGF, or formation of endothelial tubules (p=>0.05), although stimulated eTie2-iBMMs secreted significantly greater levels of MCP-1 (p=0.0022). Cell retention was significantly enhanced in ischaemic murine hindlimbs treated with eTie2-iBMMs (p=0.0083) and this was associated with significantly greater limb perfusion over 21 days (p=0.0005).
Conclusion:
Alginate encapsulation of pro-arteriogenic macrophages is not detrimental to their viability or phenotype, and increases their retention and regenerative capacity in the ischaemic hindlimb. Translation of this methodology to a clinical setting may enhance the efficacy of novel cell-based therapies for the treatment of CLI.