Background. Chronic ulcers pose a significant health concern and economic burden. Numerous products, including animal-derived collagen products, have been designed to provide the injured site with a biocompatible structural matrix that promotes tissue regeneration. Yet, animal-derived collagens can evoke immune responses, bear risk of disease transmission, and fail to closely mimic the function of native collagen. Objective. This study aims to assess the safety and performance of a novel flowable wound matrix, formulated from tobacco plant-purified fibrillated recombinant human type I collagen (rhCollagen), in patients with chronic lower limb ulcers. Materials and Methods. This single-arm, open-label, multicenter trial took place at 5 treatment centers. Wounds were photographed and preliminary surgical debridement was performed prior to rhCollagen application. Patients received a single application of rhCollagen to the wound bed, followed by weekly assessments of the wound. Results. Twenty patients (mean age, 63 years), presenting with a chronic ulcer of neuropathic (45%), posttraumatic (35%), postoperative (10%), and venous (10%) origin, underwent rhCollagen treatment. Initial wound area ranged between 0.2 cm³ to 9.2 cm³. At 4-weeks posttreatment, median wound area reduction was 94%. Fifteen ulcers exhibited ≥ 70% wound closure, 9 of which achieved complete closure. Only 1 participant suffered a local self-resolving wound infection. No significant device-related adverse events were reported throughout the study. Conclusions. A single, easy-to-use rhCollagen flowable gel application for chronic lower limb ulcers may promote wound closure with minimal adverse events.

Increased life expectancy, accompanied by a greater risk of chronic diseases, are associated with a heightened incidence of chronic wounds requiring medical care. Chronic wounds, such as venous, arterial, pressure, and diabetic ulcers, are often associated with advanced age, compromised blood supply, patient immobility, and systemic illnesses.^1,2 Each year, nearly 4 million individuals in the United States experience some form of a chronic skin ulcer.³ These wounds are painful, unsightly, and can require limb amputation if left unattended or treated inappropriately. Chronic wounds pose a significant challenge to health care providers who often adopt a multidisciplinary approach to reach effective results.⁴ Proper and timely intervention can impact time to healing, hospital length of stay and costs, pain levels, scar tissue, and overall patient quality of life.^5,6

Wound repair and tissue regeneration are complex physiological processes involving programmed matrix disassembly for the purpose of renewed growth and reorganization.^7,8 After clot formation, fibroblasts migrate into the wound region and biochemically alter the extracellular matrix (ECM) by degrading fibrin and producing collagen that replaces the blood clot. Collagens, the main structural proteins of the ECM,^9,10 control many cellular functions related to wound healing, including cell shape, differentiation, migration, and protein synthesis.^11,12

Collagen-based wound dressings or tissue substitutes contribute to local hemostatic and chemotactic stimuli while supplying a structural support scaffold upon which new tissue can be formed at an enhanced rate.^10,13 Intimate contact between applied therapeutic matrices and deep, irregularly shaped wound beds provides the basic elements required for tissue regeneration, thereby expediting healing. Current commercially available, flowable collagen wound matrix products are typically formulated from collagen purified from bovine or cadaver sources, which introduce several risks including possible exposure to pathogens and allergic reactions.

In an attempt to develop an alternative to animal tissue-derived wound care products, the authors designed a biocompatible flowable gel integrating virgin recombinant human type I collagen (rhCollagen; VergenixFG; CollPlant, Ness Ziona, Israel), expressed and purified from plants (Figure 1).¹⁴ The present study evaluated the safety and performance of rhCollagen in patients with chronic lower limb ulcers.

This single-arm, open-label, multicenter clinical study was conducted in 3 Maccabi Health Care Wound Clinics (Tel Aviv) as well as at Assaf Harofeh Medical Center (Be’er Ya’akov) and at Meir Medical Center (Kfar Saba), all located in Israel.

Ethical approval
The study protocol was approved by the Israeli Ministry of Health (Jerusalem, Israel) and the Ethics Committee/Institutional Review Boards of Asuta Medical Cener (Tel Aviv, Israel), Maccabi Health Care Services (Tel Aviv, Israel), Assaf Harofeh Medical Center, and Meir Hospital. All patients provided written, informed consent before initiating participation.

Inclusion criteria
Patients 18 years of age or older with a chronic neuropathic (University of Texas Wound Classification 1A), venous, posttraumatic, or postoperative lower limb wound measuring 1 cm² to 20 cm² that scored ≥ E on the granulometer scale were eligible to participate in the study.

Exclusion criteria
Patients with an acute ulcer (≤ 4 weeks), multiple ulcers (≥ 2), clinical evidence of infection by physical examination, hemoglobin A_1C > 12, ankle-brachial index < 0.45, an immunosuppressed state, active malignant disease, end-stage renal failure, liver dysfunction, positive pregnancy test at enrollment, known hypersensitivity and/or allergy to collagen, or participating in any other clinical trials were excluded from the study.

rhCollagen flowable gel dressing
The rhCollagen flowable gel dressing is an advanced wound care device primarily comprised of lyophilized tobacco plant-purified type I recombinant human collagen and hydroxy propyl methyl cellulose for the management of acute and chronic wounds. Recombinant human type I collagen is supplied as a powder in a syringe that is hydrated with saline just before application to form a gel.

Treatment protocol
All wounds were photographed prior to treatment with rhCollagen. Blood chemistry and complete blood count (CBC) were performed at baseline.

A preliminary surgical wound debridement was performed until viable wound bed tissue was reached. Recombinant human type I collagen was applied once to the wound bed by using one or two 2-cc doses of the gel to cover the whole wound area, followed by placement of a secondary dressing (sterile gauze pad [Nissan Medical Industries, Ltd., Israel]) (Figure 2). Patients returned to the clinic weekly ± 2 days thereafter for wound debridement; wound size, granulation, and epithelialization assessments; and application of polyurethane dressing.

In addition, wound margins were assessed using the Draize scale¹⁵ and neuropathic ulcers were classified using the University of Texas Wound Classification System.¹⁶ Patients rated pain in the wounded area using a standard point (1–10) visual analogue scale (VAS). Wounds were photographed at each visit (Canon pocket camera; Tokyo, Japan). All reports of adverse events, infection, and change in concomitant medications were recorded throughout the study. Blood chemistry and CBC were drawn again at the last visit.

Data and statistical analysis
Data were analyzed using the SAS version 9.3 software (SAS Institute, Cary, NC). Paired t test or signed rank test for 2 means for paired observations were applied, as appropriate, to test the statistical significance of changes in wound size and percent of granulation and epithelialization at follow-up visits as compared with baseline. A 95% confidence interval was calculated for the proportion of patients with signs of infection. All tests were 2-tailed, and P < .05 was considered statistically significant.

Baseline patient characteristics are presented in Table 1. Twenty patients were enrolled in the study, 16 (80%) of whom were men. Mean patient age was 63 ± 12 years. Nine (45%) patients presented with a chronic neuropathic lower limb ulcer, 7 (35%) were diagnosed with a posttraumatic lower limb ulcer, 2 (10%) with a postoperative lower limb ulcer, and 2 (10%) with a venous lower limb ulcer. Granulation tissue at baseline was present in all wounds, with 16 (80%) patients showing granulation over 75% to 100% of the wounded area. Fourteen (70%) patients showed marginal epithelialization at baseline. All wound secretions were thin and transparent and were categorized as minimal in 17 (85%) patients and as moderate in 3 (15%).

As per the data summarized in Table 2, rhCollagen application led to an overall wound size reduction (Figure 3). Overall, a mean wound size reduction of 79% within 4 weeks of treatment was observed (Table 2; P < .001). Median wound size reduction was 94%. Fifteen patients achieved > 70% wound closure, 9 of whom exhibited closure within 4 weeks of treatment. Only 1 patient failed to respond to treatment. No significant change in granulation or epithelialization were observed in the treated patients. During the study period, 18 (90%) patients presented with ≥ 75% to 100% granulation tissue in the wound bed, and 17 (85%) patients continued to show epithelization. No necrotic tissue was noted following treatment, with the exception of 2 patients, 1 of whom suffered from peripheral vascular disease. Summary of wound size reduction per patient is shown in Table 3.

All patients reported a 50% reduction in pain levels, as expressed in a decline in VAS score from a mean of 1.95 at baseline to 1.00 by week 4. No ulcer-associated infection or signs of infection were observed at the final study visit. One patient presented with wound contamination at visit 3 and 2 different patients at visit 4, all of which resolved with no sequelae within the study period. At the end of the study, wound secretions were mostly minimal, thin, and transparent. Cases of erythema (n = 1) and edema (n = 4) were recorded during the study, but all resolved within 1 week of appearance. No inflammatory response, edema, or erythema was observed at the last visit. No serious adverse events were recorded during the study period. No significant laboratory findings were recorded.

Selection of a proper wound dressing is one of the most important parts of the treatment protocol in the management of chronic ulcers. This pilot study evaluated the safety and efficacy of a single application of rhCollagen on chronic lower limb ulcers with the primary goal of assessing safety.

The current study showed the mean wound size declined by 80%, granulation tissue and epithelization were promoted in 85% of wound beds, complete wound closure was achieved in 45% of the patients, and reported pain levels decreased by 50% within 4 weeks of treatment. Most of the reported adverse events were mild, with only 1 case of a self-resolving local infection.

The introduction of collagen to the wound environment is speculated to break the vicious nonhealing cycle. Some mechanisms suggested to drive this shift include reduction of elastase and matrix metalloproteinase activity¹⁷ and promotion of angiogenesis and fibroblast chemotaxis.^18,19 The effect of collagen on wound healing has been shown to be optimal when provided in its native and structurally intact form, and it has been demonstrated to be superior to nonpurified animal-derived collagen.²⁰

Consequently, the authors of this paper assumed that a recombinant, native human collagen will provide optimal wound healing support as compared with other collagen products.

To date, several studies have demonstrated the efficacy of animal-derived collagen-based dressings in nonhealing wounds. Most of these studies ranged from daily to biweekly collagen dressing applications and achieved a lower wound size reduction rate (45%–80%) as compared with the present study results within 12 to 24 weeks of treatment. Furthermore, those studies used animal-derived collagen, including porcine, ovine, and fish.^21-26 Mostow et al²¹ performed a controlled, comparative analysis of the effect of porcine ECM biomaterial versus compression dressing on chronic wound healing. Following 12 weeks of follow-up, 55% of wounds fully healed compared with 34% of the control group (P = .02), with no reports of recurrence at 6 months.²⁰ After application of a dressing comprised of fish-derived collagen on chronic foot ulcers, initially daily and later every 3 to 4 days, Chalimidi et al²² observed complete wound closure within 8 weeks in 51% of patients compared with 50% of patients using betadine alone. The present study achieved complete wound healing in 45% of the treated cohort within 4 weeks as well as a significant reduction in wound size in most patients. Thus, as compared with reports on animal-derived collagens incorporated in wound dressings, rhCollagen proved more potent.

To the best of the authors’ knowledge, this is the first study conducted using rhCollagen for the treatment of chronic ulcers.

The present study design has several limitations that hold the authors from drawing definitive conclusions regarding rhCollagen efficacy. The study has no control group to compare with wound healing or with a more traditional product. Still, when comparing against published wound healing data from the literature, the present outcomes are still superior. Second, the follow-up time is relatively short for a chronic wound healing process assessment. Those limitations were discussed during the study design phase, and the authors decided to first assess short-term applicability and safety and to assess comparative outcomes and long-term follow up in the next trial.

A single application of rhCollagen to chronic lower limb ulcers provides a safe and effective means of optimizing wound healing. Its ease of use, improved safety, and lack of repeated application needed make it a promising tool for the treatment of nonhealing wounds.

Authors: Itay Wiser, MD, PhD^1,2; Eran Tamir, MD³; Hanna Kaufman, MD⁴; Elad Keren, MD⁵; Shalom Avshalom, MD⁶; Doron Klein, MD¹; Lior Heller, MD¹; and Eyal Shapira, MD¹

Affiliations: ¹Department of Plastic Surgery, Assaf Harofeh Medical Center, Zerifin, Israel; ²Department of Epidemiology and Public Health, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; ³Maccabi Health Care Services, Diabetic Institute, Maccabi Hashalom, Tel Aviv, Israel; ⁴Maccabi Health Care Services, Wound Clinic, Haifa, Israel; ⁵Maccabi Health Care Services, Wound Clinic, South District, Beer Sheva, Israel; and ⁶Plastic and Reconstructive Surgery Department, Meir Medical Center, Kfar Saba, Israel

Correspondence: Doron Klein, MD, Resident, Assaf Harofeh Medical Center, Plastic Surgery, Be’er Ya’akov, 70300 Israel; doroniklein@gmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.