VEGF overexpressed mesoangioblasts enhance urethral and vaginal recovery following simulated vaginal birth in rats

Vaginal birth causes pelvic floor injury which may lead to urinary incontinence. Cell therapy has been proposed to assist in functional recovery. We aim to assess if intra-arterial injection of rat mesoangioblasts (MABs) and stable Vascular Endothelial Growth Factor (VEGF)-expressing MABs, improve recovery of urethral and vaginal function following simulated vaginal delivery (SVD). Female rats (n = 86) were assigned to either injection of saline (control), allogeneic-MABs (MABs^allo), autologous-MABs (MABs^auto) or allogeneic-MABs transduced to stably expressed VEGF (MABs^allo-VEGF). One hour after SVD, 0.5 × 10⁶ MABs or saline were injected into the aorta. Primary outcome was urethral (7d and 14d) and vaginal (14d) function; others were bioluminescent imaging for cell tracking (1, 3 and 7d), morphometry (7, 14 and 60d) and mRNAseq (3 and 7d). All MABs injected rats had external urethral sphincter and vaginal function recovery within 14d, as compared to only half of saline controls. Functional recovery was paralleled by improved muscle regeneration and microvascularization. Recovery rate was not different between MABs^allo and MABs^auto. MABs^allo-VEGF accelerated functional recovery and increased GAP-43 expression at 7d. At 3d we detected major transcriptional changes in the urethra of both MABs^allo and MABs^allo-VEGF-injected animals, with upregulation of Rho/GTPase activity, epigenetic factors and dendrite development. MABS^allo also upregulated transcripts that encode proteins involved in myogenesis and downregulated pro-inflammatory processes. MABs^allo-VEGF also upregulated transcripts that encode proteins involved in neuron development and downregulated genes involved in hypoxia and oxidative stress. At 7d, urethras of MABs^allo-VEGF-injected rats showed downregulation of oxidative and inflammatory response compared to MABS^allo. Intra-arterial injection of MABs^allo-VEGF enhances neuromuscular regeneration induced by untransduced MABs and accelerates the functional urethral and vaginal recovery after SVD.