Chemotherapy, Microvascular Function, and Angiogenesis ‐ a Longitudinal Study

Abstract

RationaleAnti‐cancer therapies (CTx), such as anthracyclines (e.g., doxorubicin, Dox), have known anti‐angiogenic effects in vitro, and inhibition of angiogenesis has known cardiotoxic effects. Cardiovascular (CV) toxicities that result from CTx significantly contribute to the morbidity and mortality of breast cancer survivors. While the negative impact of CTx, including Dox, on isolated cardiomyocytes is well‐established, significantly less is known about the effects of CTx on microvascular (MV) function and angiogenic potential in patients. Our goal was to understand how CTx damages the microcirculation in order to further the understanding of mechanisms that contribute to systemic cardiovascular toxicity. Utilizing a longitudinal study design of neoadjuvant breast cancer patients, adipose tissue was collected before, during, and after CTx treatment.MethodsAngiogenic potential was evaluated using a matrigel angiogenesis assay of patient adipose. Data are presented as a percentage of wells with capillary sprouts and area of capillary sprouting ± standard error. In addition, we investigated the expression of a subset of genes involved in angiogenesis regulation (initiation/sprouting, migration, ECM remodeling, maturation, and permeability). Freshly isolated microvessels were evaluated for dilation to flow (FMD) and acetylcholine (Ach). Cardiac function was monitored via standard clinical echocardiogram. Significance was determined using paired t‐test (p ≤ 0.05*).ResultsPercentage of wells with capillary sprouts was impaired in adipose samples collected during CTx (26.3% ± 13.6%, N=4) and one month post CTx (44.3% ± 9.1%*, N=9) compared to pre‐CTx (67.1% ± 4.7%*, N=13). However, sprouting area only changed during CTx (15.0 mm2± 8.5*, N=4) compared to pre‐CTx (68.3 mm2± 10.2, N=13). One month post CTx, the sprouting area (56.8 mm2± 19.1, N=9) was not significantly different than pre‐CTx. Supporting this change in angiogenesis function, we observe changes in expression of genes involved in initiation of angiogenesis during CTx (VEGFA, VEGFB, FLT1) that show recovery of expression post‐CTx. We also observe changes in expression of genes involved in maturation of angiogenesis post CTx (KLF4, VCAM1, MMP8). Some clinical signs of reduced cardiac function were observed post CTx after microvascular and angiogenic changes were observed.ConclusionOur data show pathological impairment in angiogenic potential and gene expression in adipose tissue of breast cancer patients in a longitudinal study. These data support our observed defects in MV function (response to FMD and Ach) during and after CTx treatment. We observed significant reductions in MV function and capillary sprouting during treatment with CTx in the absence of a clinically relevant reduction in cardiac function. Our findings suggest that CTx‐induced MV dysfunction precedes and may contribute to future adverse CV events.