Bone marrow derived autologous cell therapy (ACT) has been shown to significantly reduce the rate of major amputation at 5 years in people with diabetes who developed critical limb-threatening ischemia (CLTI).
In a study of 130 patients, 64% of 42 patients who were treated conservatively needed a major amputation at 5 years versus just 30% of 45 patients who had been treated with ACT (P = .011).
This compared favorably to the results seen with repeated percutaneous angioplasty (re-PTA), where just 20.9% of 43 patients underwent limb salvage (P = .002 vs. conservative therapy).
Furthermore, amputation-free survival was significantly longer in both active groups, Michal Dubský, MD, PhD, FRSPH, reported at the annual meeting of the European Association for the Study of Diabetes.
Dr. Dubský, of the Institute for Clinical and Experimental Medicine and Charles University in Prague, also reported that fewer patients who had undergone re-PTA or ACT than conservative treatment had died by 5 years (25.8% and 35.6%, respectively, vs. 61.9%), but that the difference was significant only for the revascularization procedure (P = .012).
Based on these findings, “we believe that autologous cell therapy seems to be an appropriate alternative to repeated PTA even for patients with no-option chronic limb-threatening ischemia,” he said.
“This is a very important area,” said Andrew J.M. Boulton, MBBS, MD, FRCP, who chaired the oral abstract presentation session during which the findings were presented.
“It is very difficult to get an evidence base from randomized studies in this area, because of the nature of the patients: They’re very sick and we all deal with them in our clinics very regularly,” added Dr. Boulton, professor of medicine within the division of diabetes, endocrinology and gastroenterology at the University of Manchester (England).
Dr. Boulton called the findings a “very important addition to what we know.”
New option for no-option CLTI
CLTI is associated with persistent pain at rest, ulcers, and gangrene, and can be the end result of longstanding peripheral arterial disease. Within the first year of presentation, there’s a 30% chance of having a major amputation and a 25% chance of dying.
Importantly, said Dr. Dubský, “there is a big difference in this diagnosis” between patients with diabetes and those without. For instance, CLTI is more diffuse in patients with diabetes than in those without, different arteries are affected and the sclerosis seen can be more rigid and “full of calcium.”
While surgery to improve blood flow is the standard of care, not everyone is suitable. Bypass surgery or endovascular procedures can be performed in only 40%-50% of patients, and even then a therapeutic effect may be seen in only a quarter of patients.
“We need some new therapeutic modalities for this diagnosis, and one of them could be autologous cell therapy,” said Dr. Dubský.
Study details
Dr. Dubský and coinvestigators consecutively recruited 130 patients with diabetic foot and CLTI who had been seen at their clinic over a 5-year period. Of these, 87 had not been eligible for standard revascularization and underwent ACT or were treated conservatively.
Of the patients who were not eligible for standard revascularization (‘no-option CLTI), 45 had undergone ACT and 42 had been treated conservatively. Dr. Dubský acknowledged that “his study was not prospective and randomized.”
All patients in the study had at least one unsuccessful revascularization procedure and diabetic foot ulcers, and low tissue oxygenation. The latter was defined as transcutaneous oxygen pressure (TcPO2) of below 30 mm Hg.
There were little differences in demographic characteristics between the treatment groups, the average age ranged from 62 to 67 years, there were more men (70%-80%) than women; most patients (90%) had type 2 diabetes for at least 20 years. There were similar rates of ischemic heart disease, hypertension, dialysis, and immunosuppressive therapy.
There were no differences in baseline values of TcPO2 between the groups, and similar improvements were seen in both the ACT and re-PTA groups versus conservative group.
ACT in practice
With such promising results, what about the practicalities of harvesting a patient’s bone marrow to make the ACT?
“Bone marrow harvesting usually takes about 20 minutes,” Dr. Dubský said. It then takes another 45 minutes to separate the cells and make the cell suspension, and then maybe another 10 minutes or so to administer this to the patient, which is done by injecting into the calf muscles and small muscles of the foot, aided by computed tomography. The whole process may take up to 2 hours, he said.
“Patients are under local or general anesthesia, so there is no pain during the procedure,” Dr. Dubský reassured. “Afterwards we sometimes see small hematoma[s], with low-intensity pain that responds well to usual analgesic therapy.”
Computed tomography was used to help guide the injections, which was advantageous, Dr. Boulton pointed out, because it was “less invasive than angioplasty in these very sick people with very distal lesions, many of whom already have renal problems.”
“It is surprising though, that everybody had re-PTA and not one had vascular surgery,” he suggested. Dr. Boulton added, however: “These are very important observations; they help us a lot in an area where there’s unlikely to be a full RCT.”
The next step in this research is to see if combining ACT and re-PTA could lead to even better results.
The study was funded by the Czech Republic Ministry of Health. Dr. Dubský had nothing to disclose. Dr. Boulton made no statement about his conflicts of interest.