Therapeutic Potential of Adipose-Derived Therapeutic Factor Concentrate for Treating Critical Limb Ischemia

Abstract

Transplantation of adipose-derived stem cells (ADSCs) is an emerging therapeutic option for addressing intractable diseases such as critical limb ischemia (CLI). Evidence suggests that therapeutic effects of ADSCs are primarily mediated through paracrine mechanisms rather than transdifferentiation. These secreted factors can be captured in conditioned medium (CM) and concentrated to prepare a therapeutic factor concentrate (TFC) composed of a cocktail of beneficial growth factors and cytokines that individually and in combination demonstrate disease-modifying effects. The ability of a TFC to promote reperfusion in a rabbit model of CLI was evaluated. A total of 27 adult female rabbits underwent surgery to induce ischemia in the left hindlimb. An additional five rabbits served as sham controls. One week after surgery, the ischemic limbs received intramuscular injections of either (1) placebo (control medium), (2) a low dose of TFC, or (3) a high dose of TFC. Limb perfusion was serially assessed with a Doppler probe. Blood samples were analyzed for growth factors and cytokines. Tissue was harvested postmortem on day 35 and assessed for capillary density by immunohistochemistry. At 1 month after treatment, tissue perfusion in ischemic limbs treated with a high dose of TFC was almost double (p < 0.05) that of the placebo group [58.8 ± 23 relative perfusion units (RPU) vs. 30.7 ± 13.6 RPU; mean ± SD]. This effect was correlated with greater capillary density in the affected tissues and with transiently higher serum levels of the angiogenic and prosurvival factors vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). The conclusions from this study are that a single bolus administration of TFC demonstrated robust effects for promoting tissue reperfusion in a rabbit model of CLI and that a possible mechanism of revascularization was promotion of angiogenesis by TFC. Results of this study demonstrate that TFC represents a potent therapeutic cocktail for patients with CLI, many of whom are at risk for amputation of the affected limb.

Serum C-peptide level correlates with the course of muscle tissue healing in the rabbit model of critical limb ischemia

“…In our previous study using the rabbit model of critical limb ischemia, we demonstrated that ASC-CM can accelerate neovascularization and significantly improve ischemic tissue reperfusion 8 . A possible mechanism of revascularization was the promotion of angiogenesis by the growth factors and cytokines in the ASC-CM-treated group.…”

“…Adipose tissue was obtained from a single male patient (40 years of age, BMI 54 kg/m 2 ) undergoing elective lipoplasty. The tissue was processed for stromal vascular fraction (SVF) isolation using a Cytori Celution device as described previously 8 . Preparation and characterization of ASC-CM was performed as in the previous study 8 .…”

“…The tissue was processed for stromal vascular fraction (SVF) isolation using a Cytori Celution device as described previously 8 . Preparation and characterization of ASC-CM was performed as in the previous study 8 . The characteristics of cell populations from freshly obtained SVF and cultured ASCs are shown in Table 1.…”

“…Characterization of ASC-CM was published 8 and is summarized in Table 1. Levels of selected angiogenic and inflammatory cytokines and growth factors in 50fold concentrated TFC (therapeutic factor concentrate) were compared to human serum.…”

“…In our previous study 8 , we demonstrated in the rabbit model of critical limb ischemia that adipose-derived stem cell-conditioned medium (ASC-CM) can accelerate neo-vascularization and significantly improve ischemic tissue reperfusion.…”