Effect of diabetes on hypoxic microvascular remodeling and muscle damage in chronic limb threatening ischemia

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Finnish Academy/Research Council of Finland. The Finnish Foundation for Cardiovascular Research

Hypoxia-induced arterialization of skeletal muscle capillaries has recently been identified as an important pathological feature that aggravates ischemic damage in chronic limb threatening ischemia (CLTI). Diabetes is also known to worsen the outcome of CLTI patients but its contribution to capillary arterialization and skeletal muscle pathology under ischemia is still largely unknown.

To study how diabetes affects capillary arterialization and skeletal muscle pathology in CLTI.

Amputation muscle samples from CLTI patients (n=21 patients x3 samples) were histologically analyzed, grouped according to microvascular changes and RNA sequencing was performed. Differentially expressed genes, differentially regulated signaling pathways and histology between diabetics and non-diabetics were studied among corresponding microvascular groups. Also, spatial transcriptomics (n=2 patients) was applied to understand the mechanisms through which diabetes alters differential capillary responses on the tissue level.

Diabetes differentially regulated gene expression of different angiogenic and arteriogenic factors including HIF1A, VEGFA, FLT1, NOTCH1, NOTCH3, NOS1 and ITGB3 in the CLTI muscles. This differential transcriptomic regulation translated as increased sprouting on the level of muscle capillaries, and also affected myofiber pathology. Muscle samples in diabetic patients often presented myofiber swelling and cell death that were uncommon in samples of non-diabetic patients.

Diabetic patients on the level of muscle transcriptional regulation show changes that can explain observed differential microvascular remodeling and worsened myofiber pathology. These results broaden our understanding of the causes for the exceptionally bad outcome of diabetics among CLTI patients.