Safety of a non-viral plasmid-encoding dual isoforms of hepatocyte growth factor in critical limb ischemia patients: a phase I study

Insights into gene therapy for critical limb ischemia: the devil is in the details

Patients with critical limb ischemia (CLI) without potential for revascularization are currently without alternate therapies. Several gene therapy trials have tested angiogenesis factors, hepatic growth factor, vascular endothelial growth factor, and basic fibroblast growth factor, in rescuing CLI patients from amputation and mortality, and for improved quality of life including decreased pain, improved healing, and blood flow. Trial results have been variable, with HGF gene therapy being the most successful. New studies examining each of these angiogenic factors provide insights that will be useful for the design of effective therapeutic strategies.

A phase I clinical study of naked DNA expressing two isoforms of hepatocyte growth factor to treat patients with critical limb ischemia

BACKGROUND

The purpose of the present phase I clinical trial was to evaluate the safety, tolerability, and preliminary efficacy of naked DNA therapy expressing two isoforms of hepatocyte growth factor (pCK-HGF-X7) in critical limb ischemia (CLI) patients.

MATERIALS AND METHODS

Twenty-one patients with CLI were consecutively assigned to receive increasing doses (cohort I: 4  mg; cohort II: 8  mg; cohort III: 12  mg; and cohort IV: 16  mg) of pCK-HGF-X7, which was administered into the ischemic calf and/or thigh muscle at days 1 and 15. A safety and tolerability evaluation and measurement of pain severity score using a visual analog scale (VAS), ulcer status, transcutaneous oxygen (TcPO(2) ) and ankle-brachial index (ABI) were performed throughout a 3-month follow-up period.

RESULTS

No serious adverse events were observed in any of the 21 patients for the 3-month follow-up period. A significant reduction in pain was observed in the treated patients, with the mean VAS decreasing from 5.95-1.64 (p  <  0.001). The mean ABI value increased from 0.49-0.63 (p  =  0.026) at 3-month follow-up. The mean TcPO(2) value on the dorsum of the foot, the anterior calf and posterior calf significantly increased from 28.25-39.28  mmHg (p  =  0.012), from 22.00-30.63  mmHg (p  =  0.046) and 32.05-47.19  mmHg (p  =  0.001) at 3-month follow-up, respectively. Wound healing improvement was observed in the six of nine patients that had an ulcer at baseline.

CONCLUSIONS

These results support the performance of a phase II randomized controlled trial with pCK-HGF-X7.

A novel mechanism in maggot debridement therapy: protease in excretion/secretion promotes hepatocyte growth factor production

Maggot debridement therapy (MDT) is effective for treating intractable wounds, but its precise molecular mechanism, including the association between MDT and growth factors, remains unknown. We administered MDT to nine patients (66.3 ± 11.8 yr, 5 male and 4 female) with intractable wounds of lower extremities because they did not respond to conventional therapies. Significant increases of hepatocyte growth factor (HGF) levels were observed in femoral vein blood during 48 h of MDT (P < 0.05), but no significant change was found for vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), transforming growth factor-β1 (TGF-β1), or tumor necrosis factor-α (TNF-α). We conducted NIH-3T3 cell stimulation assay to evaluate the relation between HGF and protease activity in excretion/secretion (ES) derived from maggots. Compared with the control group, HGF was significantly higher in the 0.05 μg/ml ES group (P < 0.01). Furthermore, protease inhibitors suppressed the increase of HGF (P < 0.05). The HGF expression was increased in proportion to the ES protein concentration of 0.025 to 0.5 μg/ml. In fact, ES showed stronger capability of promoting HGF production and less cytotoxicity than chymotrypsin or bromelain. HGF is an important factor involved in cutaneous wound healing. Therefore, these results suggest that formation of healthy granulation tissue observed during MDT results from the increased HGF. Further investigation to identify molecules enhancing HGF expression by MDT will contribute greatly to drug target discovery for intractable wound healing therapy.