Angiogenin Released from ABCB5+ Stromal Precursors Improves Healing of Diabetic Wounds by Promoting Angiogenesis

Severe angiopathy is a major driver for diabetes associated secondary complications. Knowledge on underlying mechanisms essential for advanced therapies to attenuate these pathologies is limited. Injection of ABCB5+ stromal precursors (SPs) at the edge of non-healing diabetic wounds in a murine db/db model, closely mirroring human type II diabetes, profoundly accelerates wound closure. Strikingly, enhanced angiogenesis was substantially enforced by the release of the ribonuclease angiogenin from ABCB5+ SPs. This compensates for the profoundly reduced angiogenin expression in non-treated murine and human chronic diabetic wounds. Silencing of angiogenin in ABCB5+ SPs prior to injection significantly reduced angiogenesis, reduced numbers of M2 macrophages and delayed wound closure in diabetic db/db mice implying an unprecedented key role for angiogenin in tissue regeneration in diabetes. These data hold significant promise for further refining SPs-based therapies of non-healing diabetic foot ulcers and other pathologies with impaired angiogenesis. Total RNA was isolated either from FACS sorted HUVEC co-culture with wildtype and db/db murine dermal fibroblasts or artery and vein tissues from wildtype and db/db mice. Total from total skin was first rRNA depleted using either Ribominus Eukaryotic system v2 kit (ThermoFisher Scientific). rRNA depleted RNA was subjected to preparation of Illumina compatible RNA-seq libraries using NEBNext Ultra II Directional RNA Library Prep Kit (NEB). RNA-seq libraries were quality controlled through Qiaxcel advanced system (Qiagen) and finally measured by Qubit fluorimeter (ThermoFisher Scientific). Validated libraries were sequenced on Illumia Novaseq 6000 system using S1 and S2 kit (2x 100 cycles) (MLL Dx GmbH) .