In Vivo Anti-microRNA Treatment In a Humanized Mouse Model for Allograft Vasculopathy

---

M.M.H. Huibers, L. Qin, G. Li, J. Renes, C.L. Venema, E. Siera-de Koning, J. van Kuik, A.L.M. Peeters, G. Tellides, R.A. de Weger

Chair(s): Dr. E.M. van Maarseveen

Thursday 9 march 2017

12:45 - 13:00h

Categories: Poster - Basaal

Parallel session: Postersessie - Basaal 2

---

A limitation in the field of heart transplantation is cardiac allograft vasculopathy which is a diffuse concentric proliferation of the intima of coronary arteries leading to graft failure. An up regulation of several microRNAs (miRs), especially miR-21 and miR-146b-5p, is found in cardiac allograft vasculopathy patients. These miRs might act as potential therapeutic targets. Our aim is to investigate whether intimal proliferation can be reduced by targeting miR-21 and miR-146b-5p in a huSCID/bg-RAG1-/-mouse model.

Immune deficient huSCID/bg-RAG1^-/- mice were transplanted with a human coronary arterial graft, injected with allogeneic human peripheral blood mononuclear cells and are intraperitoneally treated with anti-miR therapy. The (systemic) inhibition of miR-21 and miR-146b-5p expression was determined by performing quantitative polymerase chain reaction and the effect of miR inhibition on intimal size was investigated by histologic studies. The composition of cell populations in the intimal layer after treatment was studied by immunohistochemistry (CD45RO, CD68, CD20). To determine downstream effects of the anti-miR treatment messenger RNA targets were measured by quantitative polymerase chain reaction.

Injection with anti-miRs resulted not in reduced miR-21 and miR-146b-5p expression levels in the graft tissue but did in kidney and partly in heart tissue. We did not find significantly smaller intimal areas after systemic anti-miR therapy. Decreased levels of activated T cells and macrophages were found in the intimal layer of the treated mice. Due to a large variance in each of the above measurements no statistical differences were found. Subtle changes in messenger RNA expression levels were found in the graft. Interestingly, expression levels of TGFβ significantly correlated to both miR-21 and miR-146b-5p expression in the graft.

These data show that anti-miRs can affect influx of inflammatory cells into the intimal layer, but have little effect on intimal size in a humanized mouse model for allograft vasculopathy. Overall downstream messenger RNA levels show subtle changes, where specifically TGFβ correlates to levels of both miRs. The data suggest that the anti-miR treatment did change systemic effects, but the penetration at the site of the coronary artery was minimal, causing a limited effect on the intima proliferation.