Critical limb ischaemia and the response to bone marrow-derived cell therapy according to tcPO₂ measurement

Cell therapy is an emerging potential biotherapy for critical limb ischaemia (CLI) patients who are not eligible for revascularization. However, the findings on this technique's efficacy are inconsistent. Trials investigating this topic focused on the more severe CLI patients who were often beyond any therapy. Therefore, identifying those who may truly benefit from cell transplantation is now warranted. To this end, we studied the prognostic value of tcPO₂ for major amputation after 1 year in patients treated with bone marrow-derived cells.

CLI patients ineligible for revascularization were included in a cell-therapy pilot study. On inclusion, patients underwent tcPO₂ measurement in supine and sitting positions. For a tcPO₂ < 10 mmHg in the supine position, the vascular reserve was defined by tcPO₂ > 30 mmHg in the sitting position. Patients were administered intramuscular injections of mononuclear cells derived from aspirated bone marrow.

In total, 25 patients (a lower limbs) were included for analysis. At inclusion, 11 lower limbs had tcPO₂ at rest > 10 mmHg, and 16 lower limbs had a tcPO₂ < 10 mmHg. The success probability for cell therapy was 0.79 (95 % CI 0.38-0.94) and 0.44 (95 % CI 0.18-0.67), respectively (p = 0.1). Of the 16 limbs with tcPO2 < 10 mmHg, the success rate was considerably higher in patients demonstrating a tcPO₂ increase in a sitting position of over 30 mmHg (6/8, success probability 0.71, 95 % CI 0.26-0.92) compared to those without (2/8, success probability 0.15, 95 % CI 0.01-0.48, p = 0.03).

For patients with chronic CLI for whom cellular therapy is a therapeutic option, a tcPO₂ < 10 mmHg at rest, without vascular reserve (i. e. < 30 mmHg when sitting), is a prognostic indicator for poor outcome.
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