
==== Front
Int Wound J
Int Wound J
10.1111/(ISSN)1742-481X
IWJ
International Wound Journal
1742-4801
1742-481X
Blackwell Publishing Ltd Oxford, UK

39245798
10.1111/iwj.70029
IWJ70029
Original Article
Original Article
A multicentre clinical trial evaluating the outcomes of two application regimens of a unique keratin‐based graft in the treatment of Wagner grade one non‐healing diabetic foot ulcers
Armstrong et al.
Armstrong David G. 1
Orgill Dennis P. 2
Galiano Robert D. 3
Glat Paul M. 4
Carter Marissa J. https://orcid.org/0000-0002-2265-6639
5
Hanft Jason 6
Surprenant Maria 6
Isaac Adam L. https://orcid.org/0000-0001-5338-3445
7
Zelen Charles M. https://orcid.org/0000-0001-5682-7056
2 cmzelen@periedu.com

1 Division of Surgery, Keck School of Medicine University of Southern California Los Angeles California USA
2 Professional Education and Research Institute (PERI) Roanoke Virginia USA
3 Division of Plastic Surgery, Feinberg School of Medicine Northwestern University Chicago Illinois USA
4 Department of Surgery Drexel University School of Medicine Philadelphia Pennsylvania USA
5 Strategic Solutions, Inc. Bozeman Montana USA
6 Doctors Research Network Miami Florida USA
7 Foot and Ankle Specialists of the Mid‐Atlantic (FASMA) Frederick Maryland USA
* Correspondence
Charles M. Zelen, Professional Education and Research Institute (PERI), 222 Walnut Ave, Roanoke, VA 24016, USA.
Email: cmzelen@periedu.com

08 9 2024
9 2024
21 9 10.1111/iwj.v21.9 e7002904 8 2024
05 6 2024
04 8 2024
© 2024 The Author(s). International Wound Journal published by Medicalhelplines.com Inc and John Wiley & Sons Ltd.
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

Abstract

Diabetic foot complications that lead to lower extremity amputations pose a significant challenge to the entire global health system. In this multicentre clinical trial, 26 patients with chronic Wagner one diabetic foot ulcers (DFUs) were treated with a unique human keratin matrix graft applied either weekly or bi‐weekly, in addition to standard of care. The hypothesis was that bi‐weekly application would be similar to weekly application. The primary endpoint was complete wound closure by 12 weeks, and secondary endpoints included healing time, percent area reduction and weekly changes in peripheral neuropathy, pain and quality of life. In the intent‐to‐treat population, 77% (10/13) of DFUs treated with bi‐weekly application healed compared with 69% (9/13) treated with weekly application. The mean time to heal within 12 weeks in the bi‐weekly group was 61 days and in the weekly group was 54 days. The mean percent area reduction at 12 weeks was 94.7% in the bi‐weekly group compared with 84.8% in the weekly group. The number of grafts used in the bi‐weekly group was 3.9 compared with 6.2 in the weekly group. The results of this trial confirm our hypothesis that whether bi‐weekly or weekly application of the unique keratin matrix graft is used to treat nonhealing indolent DFUs, there is a high rate of complete healing. Based on these results, future studies should be conducted that further investigate the use of this novel human keratin matrix graft for the treatment of chronic DFUs.

diabetic foot ulcer
human keratin matrix graft
wound healing
ProgenaCare Global source-schema-version-number2.0
cover-dateSeptember 2024
details-of-publishers-convertorConverter:WILEY_ML3GV2_TO_JATSPMC version:6.4.8 mode:remove_FC converted:08.09.2024
Armstrong DG , Orgill DP , Galiano RD , et al. A multicentre clinical trial evaluating the outcomes of two application regimens of a unique keratin‐based graft in the treatment of Wagner grade one non‐healing diabetic foot ulcers. Int Wound J. 2024;21 (9 ):e70029. doi:10.1111/iwj.70029 39245798
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pmc1 INTRODUCTION

Globally, there are 18.6 million people who develop a diabetic foot ulcer (DFU) every year, including 1.6 million people in the United States. 1 , 2 The lifetime incidence for Type II diabetics developing a DFU is 34%, 3 which places a significant strain on patients, caregivers, healthcare providers and health systems throughout the world. In fact, DFUs account for more than 80% of all lower extremity amputations, 4 and in the United States constitute nearly one‐third of the annual direct costs for diabetes. 5 Remarkably, the 5‐year mortality rate for people who experience a DFU is 30% and exceeds 70% for individuals who suffer a major (above the ankle) amputation. 6

Furthermore, approximately 70% of DFUs heal with a good standard of care (SOC), but at least 30% progress to chronic wounds. 7 According to recent data, between 2014 and 2019 the number of Medicare beneficiaries with a wound increased from 8.2 to 10.5 million. 8 Although the overall cost for chronic wound care modestly decreased during that time, from $29.7 to $22.5 billion, 8 there remains a significant need to develop effective wound care treatments that improve outcomes, decrease costs and increase ulcer‐free and activity‐rich days. One such modality for healing chronic wounds is a human keratin matrix graft, ProgenaMatrix™ (ProgenaCare Global, LLC, Marietta, GA, USA).

ProgenaMatrix™ is a novel, advanced wound care product constructed from human keratin and is the only human keratin matrix graft commercially available (Figure 1). Keratin is a strong structural protein involved in cell–cell and cell–matrix interactions and provides strength and structure to keratinocytes. Keratinocytes, which are found in the epidermis, deposit keratin as a protective layer over the skin. Keratin has been shown to positively impact wound healing. A study published by Tang et al. 9 showed that keratin stimulates human keratinocyte migration and types IV and VII collagen expression that contribute to wound healing. Keratin also plays a role in immunomodulation during the cell activation phase of wound healing, 10 and findings from another study demonstrated that human keratin hydrogels support fibroblast attachment and proliferation in vitro. 11

FIGURE 1 ProgenaMatrix is a novel, advanced wound care product constructed from human keratin and is the only human keratin matrix graft commercially available.

The human keratin technology in this unique human keratin matrix graft is hydrated, non‐cellular, not tissue‐based, resistant to protease degradation and supports the body's own healing process. The graft is manufactured from human keratin protein which is a sustainable raw material source. The matrix is made from all‐natural components with no synthetic ingredients. It is a monolithic biomaterial made of protein and water. Keratin is the predominant protein with several keratin subtypes. The product also contains small amounts of other non‐keratin proteins. 12

This unique human keratin matrix graft is 510(k) approved for application on DFUs and other wound types and the satisfactory wound healing has been shown in numerous case studies presented at national wound care meetings. Based on this early promising data, the larger study presented here is necessary to further validate these results and identify the likelihood of wound healing with weekly versus bi‐weekly application. If similar outcomes can be achieved with bi‐weekly application, substantial savings to the health care system is possible. Due to the durable nature of the human keratin matrix graft even in the presence of proteases and a complex DFU, the authors hypothesised that bi‐weekly application may be as effective as weekly application.

2 MATERIALS AND METHODS

A prospective, randomised, multi‐centre, open‐label clinical trial of 26 patients with a history of a Wagner one chronic DFUs was performed to collect patient outcome data on the use of two treatment regimens for a unique human keratin matrix graft. In this trial, two groups of subjects with Wagner one DFUs were treated with the unique human keratin matrix graft in addition to SOC. Half of the patients received the unique human keratin matrix graft applied weekly, and the other half had the human keratin matrix graft applied bi‐weekly. To ensure allocation concealment, 26 opaque envelopes 13 for weekly application and 13 for bi‐weekly application, each containing a slip of paper designating the study group, were used. The envelopes were randomly shuffled and labelled 01‐26. When a patient was scheduled for randomisation, the appropriate envelope was delivered to the study site with a paper slip inside acknowledging his or her group assignment. There were 9 male (69%) and 4 female (31%) subjects in the weekly group with a mean age of 67.6 years. In the bi‐weekly group, the mean age was 66.5 years, and there were 8 female (61%) and 5 male (39%) subjects. SOC included offloading with a CAM boot (Foot Defender, Miami FL) or TCC (if subject's foot was too large for a boot), appropriate sharp or surgical debridement, infection management (systemic antibiotics only in conjunction with debridement) and application of non‐adherent dressing (Adaptic touch, 3M, Maplewood MN or equivalent), followed by a padded multi‐layer outer dressing (3M Coban Light, 3M, Maplewood, MN or equivalent). The study protocol was reviewed and approved by the institutional review board Advarra (Protocol #: Pro00069464), and informed consent was signed by all participants.

Patients with nonhealing DFUs (full‐thickness ulcers on the foot or ankle that do not probe to bone or joint capsule), present for more than 4 weeks, between 1 and 20 cm2 and refractory to SOC therapies were included in the study. Subjects with HbA1c greater than or equal to 13% taken at or within 3 months of the initial screening visit and serum creatinine ≥3.0 mg/dL within 6 months of randomisation or end‐stage renal disease requiring dialysis were excluded, as well as those wounds with infection, osteomyelitis or exposed bone, probes to bone or joint capsule. A complete list of the inclusion and exclusion criteria is shown in Table 1.

TABLE 1 Inclusion and exclusion criteria.

Inclusion criteria	Exclusion criteria	
Male or female 18 years of age or older

Subjects must have a diagnosis of type 1 or 2 diabetes mellitus

At randomisation subjects must have a target diabetic foot ulcer with a minimum surface area of 1.0 cm2 and a maximum surface area of 20.0 cm2

The target ulcer must have been present for a minimum of 4 weeks and a maximum of 52 weeks of standard of care prior to the initial screening visit

The target ulcer must be located on the foot with at least 50% of the ulcer below the malleolus

The target ulcer must be full thickness on the foot or ankle that does not probe to the bone

Adequate circulation to the affected foot as documented by any of the following methods performed within 3 months of the first screening visit: a. TCOM ≥30 mmHg, b. ABI between 0.7 and 1.3, c. PVR: Biphasic, d. TBI >0.6, e. As an alternative arterial, Doppler ultrasound can be performed to evaluate for biphasic dorsalis pedis and posterior tibial vessels at the level of the ankle

If the subject has two or more ulcers, they must be separated by at least 2 cm. The largest ulcer satisfying the inclusion and exclusion criteria will be designated as the target ulcer

Target ulcers located on the plantar aspect of the foot must be offloaded for at least 14 days prior to randomisation

The subject must consent to use the prescribed off‐loading method for the duration of the study

The subject must agree to attend the weekly study visits required by the protocol

The subject must be willing and able to participate in the informed consent process

	A subject known to have a life expectancy of <6 months

If the target ulcer is infected or if there is cellulitis in the surrounding skin that requires systemic antibiotic therapy

The presence of osteomyelitis or exposed bone, probes to bone or joint capsule on investigator's exam or radiographic evidence

A subject receiving immunosuppressants (including systemic corticosteroids at doses greater than 10 mg of Prednisone per day or equivalent) or cytotoxic chemotherapy

The topical application of steroids to the ulcer surface within 1 month of initial screening is not permitted

A subject with a previous partial amputation on the affected foot is excluded if the resulting deformity impedes proper offloading of the target ulcer

HbA1c greater than or equal to 13% taken at or within 3 months of the initial screening visit

Serum creatinine ≥3.0 mg/dL within 6 months of randomisation or end‐stage renal disease requiring dialysis

Target ulcer has reduced in size by more than 30% during the 2‐week screening phase

A subject with an acute Charcot foot, or an inactive Charcot foot, that impedes proper offloading of the target ulcer

Women who are pregnant or considering becoming pregnant within the next 6 months

A subject who participated in a clinical trial involving treatment with an investigational product within the previous 30 days

A subject who, in the opinion of the Investigator, has a medical or psychological condition that may interfere with study assessments

A subject treated with hyperbaric oxygen therapy or a cellular and/or tissue product (CTP) in the 30 days prior to the initial screening visit

	

All subjects underwent a screening phase, consisting of at least 14 days, to determine eligibility. At the first Screening Phase Visit (SV1), written informed consent (ICF) from the subject was obtained and the study index ulcer was selected by the investigator. Each subject could have only one DFU selected as the index ulcer, and if the subject had more than one DFU at the SV1 visit, the largest DFU meeting the eligibility criteria was selected.

During the treatment phase, eligible wounds were treated with either weekly or bi‐weekly application of the unique human keratin matrix graft, in addition to SOC. During each weekly treatment visit, the following assessments and activities were performed: changes in medical history and physical examination; assessment of concomitant medications, changes from the previous visit and prohibited therapies; vital signs; assessment of pain, blood glucose, offloading, the index ulcer foot and neuropathy with a Semmes Weinstein (SW) 10‐point test; any changes in the subject's health; assessment of any adverse effects and adverse events and index ulcer closure assessment.

For the index ulcer assessments, signs of clinical infection were checked, and if a clinical diagnosis of infection was made, the subject could be treated with oral antibiotics. However, topical antibiotics or antimicrobial dressings were not permitted to be used on the study ulcer. In addition, the index ulcer was cleaned and debrided, if appropriate. Digital imaging and recording of the index ulcer measurements were performed, as well as the application of the appropriate treatment for the index ulcer. Subjects were followed weekly for up to 12 weeks, or until the wounds were completely epithelialised and determined to be fully healed. If the index ulcer was deemed 100% re‐epithelialised, the subject was scheduled for a healing confirmation visit 2 weeks later to confirm that the wound remained completely epithelialised.

The primary study endpoint was the proportion of subjects that obtained complete closure over the 12‐week treatment period as determined by each individual site investigator. Secondary endpoints included time to achieve complete wound closure of the target ulcer by the end of 12 weeks, percentage wound area reduction (PAR) during the treatment, measured weekly, change in weekly peripheral neuropathy of the target foot, change in weekly pain in the target ulcer and change in quality of life.

3 STATISTICS

The intent‐to‐treat (ITT) and safety populations comprised randomised patients who received at least 1 treatment. The per protocol population (PP) comprised randomised patients who received at least 1 treatment, completed the study and did not have a major protocol violation. Demographic analysis used the ITT approach but analysis of the primary, secondary and exploratory endpoints used both ITT and PP populations. The last observation carried forward principle was used regarding missing area data at study visits. Study variables were summarised as means and standard deviations (±SDs) for continuous variables as well as medians for non‐normal data. Categorical variables were presented as counts and proportions or percentages. Statistical testing between treatment groups at baseline was carried out to examine the success of randomisation. For categorical variables, chi‐square or Fisher exact tests were performed and for continuous variables independent t‐tests or Mann–Whitney tests were used (depending on variable normality) to test for statistical differences. The PAR for the index wound at X weeks was calculated as ((A I  − A XW )/A I ) × 100, where A I is the area of the index wound at randomisation and A XW is the area at X weeks. Time to heal is the first date that the wound is considered healed (completely epithelialised, 0 cm2 area, with no drainage). All endpoint analyses are summaries; no hypothesis testing was carried out as given the size of this trial it would be underpowered in regard to comparative testing between treatment groups.

4 RESULTS

In this trial, 28 subjects with non‐healing DFUs were consented at 3 sites beginning in February of 2023 with 26 enrolled (two screen failures). There were 13 subjects assigned to each group, weekly and bi‐weekly application of the unique human keratin matrix graft plus SOC, respectively. One subject in the weekly group was withdrawn because of an AE in which the index ulcer worsened with a probe to the tendon. Furthermore, in the bi‐weekly group, one subject was withdrawn because of an SAE in which the diabetic foot became infected and required hospitalisation. A subject flow chart is shown in Figure 2. Comparison by treatment group of key subject‐related variables is shown in Tables 2 and 3 lists the key wound‐related variables. Notably, the variables were reasonably well balanced between the groups, especially given the relatively small numbers, although the categorical percentages of sex at birth, duration of diabetes and associated cumulative total of DFUs and number of major amputations could be different between treatment groups in terms of clinical relevance, and the wound area at randomisation was considerably larger in the bi‐weekly group. Representative cases are demonstrated in Figures 3, 4, 5.

FIGURE 2 Subject flow chart. ITT, intent‐to‐treat; PP, per protocol.

TABLE 2 Comparison by treatment group for key subject‐related variables.

Variable	ProgenaMatrix weekly	ProgenaMatrix bi‐weekly	p	
Age (years)	67.6 (9.32)	66.5 (12.34)	0.98	
Median: 69.1 (IQR: 17.4)	Median: 68.2 (IQR: 17.1)	
Race			1.0	
Caucasian	12 (92)	11 (85)		
African American	1 (85)	2 (15)		
Ethnicity			1.0	
Hispanic	11 (85)	11 (85)		
	2 (15)	2 (15)		
Sex at birth			0.24	
Male	9 (69)	5 (39)		
Female	4 (31)	8 (61)		
BMI	32.5 (8.18)	29.8 (3.44)	0.61	
Median: 30.6 (IQR: 9.5)	Median: 29.9 (IQR: 4.9)	
Smoker			0.26	
Current	2 (15)	0 (0)		
Former	2 (15)	4 (30)		
Never smoked	9 (70)	9 (70)		
HbA1c (%)				
At randomisation	7.9 (2.10)	7.0 (1.88)	0.1	
At EOS	Median: 7.0 (IQR: 2.3)	Median: 6.3 (IQR: 1.9)	0.24	
7.6 (1.57)	6.6 (1.17) a	
Median: 6.8 (IQR: 2)	Median: 6.8 (IQR: 1.7)	
Creatinine (mg/dL)	1.1 (0.31)	1.2 (0.25)	0.061	
Median: 1.0 (IQR: 0.23)	Median: 1.3 (IQR: 3.1)	
Diabetes duration (years)	17.5 (17.48)	22.8 (17.74)	0.43	
Median: 11 (IQR: 25.3)	Median: 22 (IQR: 34.5)	
History DFU recurrence	8 (62)	11 (85)	0.38	
Amputations, minor			0.59	
0	7 (53)	8 (61)		
1	4 (31)	4 (31)		
2	1 (8)	1 (8)		
3	1 (8)	0 (0)		
Major amputations	0 (0)	3 (23)	0.22	
Foot deformities (study foot) b			0.41	
Charcot	3 (23)	3 (23)		
Hallux valgus	1 (8)	0 (0)		
Cavus foot	2 (16)	0 (0)		
Pes planus	0 (0)	2 (0)		
Drop foot	1 (8)	1 (0)		
Hammer toes	0 (0)	1 (0)		
Comorbidity count	9.9 (4.57)	9.9 (3.80)	1.0	
Note: Continuous variables are reported as means (SD) with median/IQR additionally reported for key non‐normally distributed continuous variables, and categorical variables as counts (percentage).

Abbreviations: CHF, chronic heart failure; CKD, chronic kidney disease; DFU, diabetic foot ulcer; PAD, peripheral arterial disease.

a Subject's value missing.

b In the contralateral foot there was only 1 case of Cavus foot in the weekly group compared to 1 case of pes planus in the bi‐weekly group.

TABLE 3 Comparison by treatment group for key subject‐related variables.

Variable	ProgenaMatrix weekly	ProgenaMatrix bi‐weekly	p	
Wound area (cm2) a	2.2 (1.31)	3.7 (2.56)	0.11	
Median: 1.6 (IQR: 1.9)	Median: 2.5 (IQR: 4.6)	
Wound age (weeks) a	13.8 (10.64)	18.2 (22.6)	0.23	
Median: 9 (IQR: 12.9)	Median: 12.7 (IQR: 19.7)	
DFU location (1)			1.0	
Plantar	12 (92)	12 (92)		
Dorsal	1 (8)	1 (8)		
DFU location (2)			0.69	
Toe	4 (31)	3 (22)		
Fore foot	5 (37)	4 (31)		
Mid foot	2 (16)	1 (8)		
Hind foot	0 (0)	1 (8)		
Heel	2 (16)	4 (31)		
DFU position			0.69	
Medial	9 (69)	7 (54)		
Lateral	4 (31)	6 (46)		
Number of sharp debridements	5.8 (4.68)	6.2 (2.74)	0.33	
Median: 3 (IQR: 12)	Median: 5 (IQR: 5)	
History of offloading type b			0.53	
No offloading	3 (23)	2 (16)		
CAM boot	8 (61)	8 (61)		
Defender boot	1 (8)	0 (0)		
Surgical shoe	1 (8)	3 (23)		
History of offloading (weeks) c	11.9 (8.35)	13.0 (15.07)	0.83	
Median: 9.5 (IQR: 16.9)	Median: 8 (IQR: 20)	
Offloading compliance (≥95% at each visit)	6 (50)	9 (69)	0.43	
Note: Continuous variables are reported as means (SD) with median/IQR additionally reported for key non‐normally distributed continuous variables, and categorical variables as counts (percentage).

Abbreviation: DFU: diabetic foot ulcer.

a At randomisation.

b All DFUs offloaded with a CAM boot except for 1 DFU in the weekly group (a medial, plantar wound on a toe).

c Data missing for 3 values missing in the weekly group and 2 in the bi‐weekly group.

FIGURE 3 An 80‐year‐old male with chronic plantar forefoot sub met 5 DFU, present for 7 weeks. HbA1c: 6.6%, serum creatinine: 0.9 mg/dL; (A) ulcer size at screening visit 1: 1.0 cm2; (B) ulcer at treatment visit 3 and (C) wound healed at 4 weeks with 3 weekly applications of ProgenaMatrix.

FIGURE 4 A 67‐year‐old male with chronic hallux DFU, present for 4 weeks. HbA1c: 11.8%, serum creatinine: 1.26 mg/dL; (A) ulcer size at screening visit 1: 1.1 cm2; (B) ulcer at treatment visit 2 and (C) wound healed after 5 weeks with 3 bi‐weekly applications of ProgenaMatrix.

FIGURE 5 A 74‐year‐old male with chronic plantar forefoot sub met 5 DFU, present for 8 weeks. HbA1c: 7.5%, serum creatinine: 1.09 mg/dL; (A) ulcer size at screening visit 1: 1.1 cm2; (B) ulcer following one application of ProgenaMatrix and (C) wound healed with 3 weekly applications of ProgenaMatrix.

4.1 Intent‐to‐treat (ITT) analysis

For the ITT population, 77% (10/13) of DFUs treated with the bi‐weekly application of ProgenaMatrix healed compared to 69% (9/13) treated with the weekly application. The mean PAR at 12 weeks was 94.7% (SD: 11.04) in the bi‐weekly group versus 84.8% (SD: 28.68) in the weekly group. Weekly PAR values for both treatment groups are shown in Figure 6. The mean time to heal within 12 weeks in the bi‐weekly group was 61 days (95% CI: 52.1–70.4), and 54 days (95% CI: 38.2–69.7) in the weekly group. The Kaplan–Meier plot comparing healing time between the two groups is shown in Figure 7. The mean change in SW score between randomisation at end of study (EOS) visits for the bi‐weekly group was −0.5 (SD: 1.05) and 0.2 (SD: 0.44) in the weekly group whereby a positive change indicates an increase in sensitivity. The mean difference in quality of life with chronic wounds (w‐QOL) score between baseline and EOS visits for the bi‐weekly group was 0.3 (SD: 0.37) as compared to 0.2 (SD: 0.67) in the weekly group. The mean difference in NPRS pain score between baseline and EOS visits was 0.7 (SD: 0.90) in the bi‐weekly group and 0.3 (SD: 1.19) in the weekly group. The mean number of grafts used in the bi‐weekly group was 3.9 (SD: 1.55) as compared with 6.2 (SD: 4.56) in the weekly group.

FIGURE 6 Weekly percent area reduction (PAR) values for both treatment groups (intent‐to‐treat [ITT] population).

FIGURE 7 Kaplan–Meier plot of the probability of wound healing by 12 weeks (intent‐to‐treat population).

4.2 Per protocol (PP) analysis

In the PP population, 91% (10/11) of DFUs healed with the bi‐weekly application of ProgenaMatrix, and 73% (8/11) healed with the weekly application. The mean PAR in the bi‐weekly group was 96.7% (SD: 10.85) and 89.8% (SD: 20.95) in the weekly group (Figure 8). The mean time to heal in the bi‐weekly group was 59 days (95% CI: 50.1–68.2) as compared to 50 days (95% CI: 34.1–66.8) in the weekly group. Figure 9 shows the Kaplan–Meier plot of the probability of wound healing by 12 weeks in the PP population. The mean change in SW score between randomisation at EOS visits for the bi‐weekly group was 0.3 (SD: 0.47), and −0.4 (SD: 0.67) in the weekly group. For w‐QOL, the mean difference in score between baseline and EOS visits for the bi‐weekly group was 0.4 (SD: 0.34) versus 0.2 (SD: 0.58) in the weekly group. The mean difference in NPRS pain score between baseline and EOS visits was 0.8 (SD: 0.92) in the bi‐weekly group and 0.3 (SD: 1.25) in the weekly group. The mean number of grafts used in the bi‐weekly group was 3.7 (SD: 1.35) as compared with 6.0 (SD: 4.80) in the weekly group.

FIGURE 8 Weekly percent area reduction (PAR) values for both treatment groups (per protocol population).

FIGURE 9 Kaplan–Meier plot of the probability of wound healing by 12 weeks (per protocol population).

4.3 Safety analysis

There were 24 AEs allocated to 9 subjects. The bi‐weekly group had 16 AEs allocated to 5 subjects and the weekly group had 8 AEs allocated to 4 subjects. The subject AE rate in which each subject counts as 1 regardless of the number of AEs was 38% for the bi‐weekly group and 31% for the weekly PM. There were 3 SAEs, all in the bi‐weekly group whereby one subject had a diabetic foot infection that required hospitalisation. This may be related to the other concurrent DFU the subject had, but the wound involved was not noted in the CRF. One subject had gangrene of the left 3rd toe that required amputation in the hospital. One subject experienced sepsis that required hospitalisation. There were no AEs or SAEs found to be related to the unique human keratin matrix graft.

5 DISCUSSION

Complications from DFUs such as infection, hospitalisation and lower extremity amputation continue to challenge the entire healthcare spectrum, and the economic implications are significant. In fact, the incremental annual cost associated with treating patients with one or more DFUs is between $11 700 and $16 883, and the excess work‐loss costs incurred by these patients are $3259. 13 Therefore, a great need exists to develop DFU treatments that improve outcomes in this complex patient population whilst promoting healing and reducing financial burdens.

Keratin is a structural protein that provides strength and structure to keratinocytes, which are found in the epidermis, and deposit keratin as a protective layer over the skin thereby promoting skin closure and wound healing. In a study conducted by Tang et al., 9 the authors reported accelerated cell migration and stimulation of collagen expression using wool‐derived oxidised keratin (OKHP), suggesting that keratin may optimise wound healing. Another study found that a keratin biomaterial contributed to macrophage polarisation, leading to greater production of anti‐inflammatory cytokines and decreased amounts of pro‐inflammatory cytokines, both of which can be beneficial to tissue regeneration. 10 Furthermore, common proteolytic enzymes fail to significantly degrade feather keratins, as compared to microbially‐derived keratinases, 14 and the keratin biomaterials found in the unique human keratin matrix graft do not degrade in saline or in artificial wound fluid.

The unique human keratin matrix graft is 80% water by weight, and 99.4% of dry weight is keratin proteins. The matrix is a firm but flexible hydrogel, and degradation resistant. This corresponds to the treatment success of the bi‐weekly group as the matrix did not degrade significantly between consecutive treatment visits. A recent study found that in a murine chronic wound model, full‐thickness wounds treated weekly with a human keratin matrix were smaller than those treated with a human amniotic membrane, bovine dermis or porcine decellularised small intestinal submucosa. Furthermore, the wounds treated with the human keratin matrix had significantly faster closure rates compared to the other treatment modalities. 12

In this trial, two groups of subjects with chronic DFUs were treated with the unique human keratin matrix graft in addition to SOC. Half of the patients received the unique human keratin matrix graft applied weekly, and the other half had the unique human keratin matrix graft applied bi‐weekly. For the ITT population, 77% (10/13) of DFUs treated with the bi‐weekly application of ProgenaMatrix healed as compared with 69% (9/13) treated with a weekly application, and wound closure was achieved in an average of 61 days in the bi‐weekly group versus 54 days in the weekly group. The mean PAR at 12 weeks was 94.7% in the bi‐weekly group compared with 84.8% in the weekly group, and the number of grafts used in the bi‐weekly group was 3.9 compared with 6.2 in the weekly group. These healing metrics are very similar to other successful trials examining both human, synthetic and xenografts. 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22

The strength of our study includes a robust trial design with appropriate procedures for screening, a standardised approach to SOC treatment, ITT analysis and appropriate adjustments for multiple statistical testing. However, there are some weaknesses in the study, including limited sample size, lack of a control group, a lack of a large number of sites with different geographic distributions and the need for a longer follow‐up period for patients after wound healing to determine the rate of recurrence.

6 CONCLUSION

Based on the success of this trial and the success of both treatment groups, highlighting that bi‐weekly application is equally successful at healing indolent DFUs when compared to weekly application, future studies should be conducted to further investigate the use of this unique human keratin matrix graft for the treatment of chronic DFUs with a larger cohort and a SOC comparator group to validate these promising results.

FUNDING INFORMATION

This study was funded by a grant from ProgenaCare Global to the Professional Education and Research Institute, Roanoke VA.

CONFLICT OF INTEREST STATEMENT

David G. Armstrong, DPM, MD, PhD received research funds from PERI to design and administrate the trial and also assist with the writing and review of the manuscript. Dennis P. Orgill, MD, PhD received research funds to serve as a validating plastic surgeon to review the study protocol, photos and assist with the writing and review of the manuscript. Robert D. Galiano, MD received research funds to serve as a validating plastic surgeon to review study protocol, photos and assist with the writing and review of the manuscript. Paul M. Glat, MD received research funds to serve as a validating plastic surgeon to review study protocol, photos and assist with the writing and review of the manuscript. Marissa J. Carter, PhD received research funds to provide the statistical analysis plan, and provide the statistical analysis for this trial and assist with writing the result section of the manuscript. Jason Hanft, DPM is a principal investigator for Doctor Research Network and his company received research funds for enrollment in the clinical trial. Maria Surprenant DPM is a principal investigator for Doctor Research Network and her company received research funds for enrollment in the clinical trial. Adam L. Isaac DPM is a principal investigator for Foot and Ankle Specialists of the MidAtlantic and his company received research funds for enrollment in the clinical trial. Charles M. Zelen, DPM is the medical director of the PERI and his company received research funds to administrate the clinical trial and write the paper for publication. There are no other conflict of interests with any of the authors in relation to this study, or with regard to Progenacare. IRB conflict of interest statements are on file with PERI.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.
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