Intraarterial Versus Intramuscular Delivery of Autologous Bone Marrow Blood to Patients with Critical Limb Ischemia

Autologous bone marrow cell application has been proposed as an alternative therapy in patients (pts) with critical limb ischemia (CLI), not eligible for endovascular or surgical revascularization, but the way of their administration is currently unresolved. The aim of our study is to compare intramuscular (i.m.) and intraarterial (i.a.) bone marrow blood (BMB) delivery.

Fifty nine patients (median age 67 years, range 38 – 89; gender M :F = 50 :9) with advanced CLI (Rutherford category 5, 6) not eligible for revascularization underwent analgosedation with profolol and total of 240 ml of BMB from both posterior iliac crests were harvested and stabilized with heparin. Bone marrow aspirate was processed with SmartPreP2 Bone Marrow Aspirate Concentrate System (Harvest, Plymouth, MA) – gradient density centrifugation to provide 40 ml of BMB concentrate (BMBc) within 15–20 minutes. Patients were randomized to treatment with 40 ml of BMBc either using local i.m. or i.a. infusion. Primary end points were limb salvage and wound healing. Secondary end points included changes in transcutaneous oxygen pressure (tcpO₂), quality of life questionnaire (EQ 5D), ankle-brachial index (ABI), and pain scale (0–10 scale). Patients with limb salvage and wound healing were considered as responders to BMBc therapy.

Fifty nine collected BMB contained median mononucleated cell number 35, 8 × 10⁹/l (range 12, 5 – 79, 8) and CD34+ cells 237, 25 × 10⁶/l (range 57, 2 – 694, 3). Processing of BMB reduced to volume from 240 ml to 40 ml (e.g. 6x) and increased concentration of mononucleated cells and CD34+ cells (2, 9x). According to the randomization BMBc was administered i.m. (24 patients) into the ischemic limb or by means of i.a. infusion (800ml/hour) through the catheter positioned into the popliteal artery (25 patients).

Since procedure 41 patients could reach 180 days follow up, 4 patients died from unrelated reason to study and 37 patients were evaluable for response. Twenty seven of 37 had limb salvage (73%). There was significant improvement in tcpO₂ (15±10 to 29±13mmHg, p<0.001), in pain scale (4.4±2.6 to 0.9±1.4, p<0.001) and EQ 5D (51±15 to 70±13, p<0.001), and significant decrease in Rutherford category of CLI (5.0±0.2 to 4.3±1.6, p<0.01). There were no differences among functional parameters in patients undergoing i.m. versus i.a. delivery. Responders (n=27) vs. nonresponders (n=10) received higher CD34+ cells amounts in the bone marrow concentrate (29±15×10^6 vs 17±12×10^6, p<0.05), but similar number of total nucleated cells (4.3±1.4×10^9 vs 4.1±1.2×10^9, p=0.66). Responders had significantly lower C-reactive protein level (CRP 18±28 vs 100±96 mg/l, p<0.05) and white blood cell counts (8.3±2.1×10^9/l vs 12.3×4.5×10^9/l, p<0.05) at the time of study procedure.

Autologous bone marrow blood harvest and administration is safe. There is no difference in i.m. versus i.a. application, both methods of autologous BMB delivery are effective in pts with CLI. Higher CD34+ cell content in BMBc and lower degree of inflammation are associated with good response to BMB application.

Funding of project “Transplantation of autologous bone-marrow stem cells in patients with critical limb ischemia” ITMS code 26240220023 is supported by Operational programme Research and Innovation from European Regional Development Fund.

No relevant conflicts of interest to declare.