Prospective, Single-center, Open-label, Pilot Study Using Cryopreserved Umbilical Tissue Containing Viable Cells in the Treatment of Complex Acute and Chronic Wounds

Nonhealing wounds, defined as any wounds that are unable to proceed through the normal phases of wound healing in a timely manner, are reported to affect 6.5 million people in the United States.¹ Underlying conditions such as diabetes, venous insufficiency, and persistent pressure are among key contributing factors for the development of such wounds.² Nonhealing complex wounds, specifically with exposed bone, tendon, muscle, or hardware, prove to be an even greater clinical challenge to physicians. When left open for prolonged periods of time, exposed deep tissue structures are at an increased risk for infection and tissue necrosis, which leads to an increased risk of amputation.^3,4 In addition to the physical disabilities associated with amputations, this patient population tends to have a decreased quality of life and an increased mortality rate, with the 5-year rate reported to be between 40% and 70%.¹ As such, rapid granulation to cover exposed deep tissue structures and subsequent wound closure are critical for patient recovery.

The current treatment for nonhealing wounds includes aggressive debridement, especially in cases in which osteomyelitis is present, nutritional support for any underlying conditions, infection management, establishment of adequate circulation, and application of dressings to protect and cover the wound.⁵ In cases where conservative wound management is not feasible, the next option is a surgical treatment approach utilizing a local or distant skin flap to cover the wound. Unfortunately, as often is the case of complex wounds, these surgical treatments are not feasible due to the severity of the wound and/or paucity of donor site.^6,7 Thus, alternative advanced therapies are employed when using flaps is not feasible or fail.

In recent years, skin substitutes have been increasingly utilized in the management of complex wounds. Examples of such products include a bilayered matrix wound dressing (BMWD), a cryopreserved split-thickness allograft, and a cryopreserved umbilical tissue containing viable cells (vCUT).^8-10 A vCUT allograft retains the extracellular matrix, growth factors, and endogenous neonatal cells, including stem cells of the native tissue, and is indicated for use as a wound cover for acute and chronic wounds.¹¹

Previously, clinical outcomes utilizing vCUT have only been described in small, retrospective case studies and reports. In 2017, Brandeisky et al¹² reported the outcomes of vCUT in the treatment of Achilles tendon rupture open repairs. Four patients received 1 surgical application of vCUT to augment Achilles tendon repair. The outcomes were compared with 4 matched control patients. Patients who received vCUT reported less pain, had minimal scarring and edema, and were able to return to work faster without any complications.¹² In a case report describing the use of vCUT in the management of a chronic rectovaginal fistula,¹³ a 60-year-old female presented with a chronic fistula that had previously failed multiple surgical repairs. Three months after the surgical fistula repair augmented with vCUT, the repair remained intact and the perineal wound had completely closed.¹³ In 2018, a case report¹⁴ described the outcomes of vCUT in the augmentation of vaginal cuff closure during laparoscopic hysterectomy in a 36-year-old female. Six weeks postop, the patient had no granulation tissue, serosanguinous fluid formation, bleeding, odor, or pain.¹⁴ Lastly, McGinness et al¹⁰ retrospectively analyzed 10 patients with complex wounds and gas gangrene who received 1 intraoperative vCUT application. All 10 patients achieved complete wound closure, with fewer complications and a shorter hospital stays, compared with historical control for inpatient management of gas gangrene.¹⁰

Although vCUT has demonstrated positive clinical outcomes in several surgical applications, all studies were retrospective in nature. Herein, the authors present the results of a single-center, prospective, pilot study of vCUT use in the treatment of acute and chronic complex wounds. 

Study population and design
This was a prospective, single-center, open-label study evaluating vCUT in the treatment of acute and chronic complex wounds. Institutional review board (IRB) approval was obtained prior to patient enrollment at the Joseph M. Still Burn Center in Augusta, Georgia. All patients provided written informed consent before any study procedures were performed. The study was conducted in compliance with the principles outlined in the Declaration of Helsinki. 

Between November 2018 and March 2019, 10 patients with 12 wounds were enrolled and received 1 application of vCUT. Patients were followed weekly for clinical and safety outcomes for an additional 4 weeks post-application. Patients 18 years or older with an acute or chronic complex wound between 5 cm² and 80 cm² were eligible for this study. Patients who had a hemoglobin A_1c of more than 14% or an arterial ulcer were not eligible for this study, nor were non-compliant patients or those with drug or alcohol abuse. 

Materials and treatment regimen
A vCUT allograft (Stravix; Osiris Therapeutics, Inc., a subsidiary of Smith+Nephew) is composed of umbilical amnion and Wharton’s jelly and is indicated for use as a wound cover in the treatment of acute and chronic wounds without restriction to etiology or location. A vCUT allograft naturally conforms to complex anatomies and may be used over exposed bone, nerves, tendon, joint capsule, muscle, hardware, and surgical mesh. All vCUT allografts are processed aseptically in a controlled, clean environment, following rigorous quality assurance standards, and then stored and distributed for use in accordance with the regulations in 21 CFR 1271 and the standards of the American Association of Tissue Banks. 

A vCUT graft is white to buff colored, about 1 mm to 3 mm in thickness, and packaged in a sterile polycarbonate jar contained within a heat-sealed pouch. To thaw, the jar is removed from the pouch and sterile saline is added directly to the jar. Once the product moves freely in the jar, it is ready for application. A vCUT graft can be stored between -75°C and -85°C and has a shelf life of 2 years.¹²

Prior to vCUT application, wounds were cleaned and debrided to remove dead and necrotic tissue. Patients then received either a 3 cm x 6 cm unit, a 2 cm x 4 cm unit, or a combination of multiple pieces in order to accommodate the size of the wound. Post-application, the wounds were dressed with a nonadherent dressing and secondary dressings when needed. The standard dressing used for patients was Mepitel (MölnlyckeHealth Care) as the nonadherent dressing, with secondary dressings including Kerlix (Covidien) and ACE wraps (3M), though this varied slightly depending on the investigator’s discretion. Patients returned weekly for an additional 4 weeks for ulcer and safety assessments.

Clinical outcomes and statistical analyses
The primary endpoint of this study was proportion of patients who achieved 100% granulation. Secondary endpoints included time to granulation, percent decrease in wound area and volume, proportion of patients who achieved wound closure, and adverse events (AEs). Outcomes were evaluated using the per-protocol (PP) population. 

Patient demographics and wound characteristics
A summary of patient demographics and wound characteristics is presented in Table 1. Ten patients with 12 complex wounds were enrolled in the study and received 1 vCUT application in the intent-to-treat (ITT) population. Eight patients were male and 2 were female, with an average age of 57 years. Of the 10 patients, 60% had diabetes mellitus (DM), 60% had hypertension (HTN), 40% had hyperlipidemia (HLD), 30% had coronary artery disease (CAD), 20% had venous insufficiency, and 10% had kidney disease. Of the 12 wounds, 4 were diabetic foot ulcers (DFUs), 2 were venous leg ulcers (VLUs), 3 were traumatic wounds, 2 were pressure wounds, and 1 was a surgical wound. The average wound area was 16.5 cm² (range, 6.0 cm²– 40.0 cm²), with an average duration of 10 months (range, 1.3–37.9 months). Two patients did not complete all 4 weeks of the study, thus were excluded from the analyses. The remaining 8 patients with 10 wounds constituted the PP population.

Clinical and safety outcomes
Clinical outcomes are presented in Table 2. Of the 10 wounds analyzed in the PP population, 8 achieved 100% granulation in a median time of 13 days (mean, 17.5 days). The median percent area reduction (PAR) was 40.5, and the median percent volume reduction was 59.4 by the end of the 4 weeks of treatment. Three of the 10 wounds achieved complete closure. There were 3 AEs reported during the study: 1 fall, 1 event of cellulitis, and 1 event of fever. The cellulitis event was determined to be the only AE possibly related to the treatment. By the end of the study, all 3 AEs had been resolved. The following 2 cases are representative of the study cases.

Case 1
A 75-year-old female with a history of CAD, basal cell carcinoma, arthritis, myocardial infarction, and chronic back pain presented to the clinic with 3 traumatic wounds of 1.3 months duration from a fall. The 3 wounds measuring 13.5 cm², 30 cm², and 6 cm² were located on the left ankle, right knee, and left leg, respectively (Figure 1A, 1D, 1G). All wounds had previously been treated with a skin autograft that failed.

Wounds were cleaned and debrided to remove any dead or necrotic tissue. The vCUT product then was applied to each of the wounds and secured using thin adhesive strips (Steri-Strips; 3M). The wounds then were dressed with a nonadherent dressing and secondary dressings. The patient was instructed to keep the dressings dry and intact and to elevate both extremities as often as possible. Per protocol, the patient was to return weekly to the outpatient clinic for 4 additional weeks.

Two weeks after the procedure, the patient experienced another fall, causing 2 new wounds on her right forearm. However, the left lower leg wound that originally measured 6 cm² had completely closed (Figure 1H). The left ankle wound decreased in size by 93.5% (0.84 cm²; Figure 1B), while the right knee wound increased in size by 50.0% (45.0 cm²; Figure 1E). At this point, no additional therapies were added to the patient’s treatment regimen for the lower extremity wounds. The patient missed the third week visit, so no measurements were obtained. By the end of the 4-week treatment period, all 3 wounds had achieved complete closure (Figure 1C, 1F, 1I). 

Case 2
A 39-year-old male with a history of venous insufficiency and gallbladder surgery presented to the clinic with a VLU of the right leg measuring 40 cm² of unknown duration (Figure 2A). The wound previously had been treated with SANTYL (Smith+Nephew).

After the wound was cleaned and debrided, vCUT was applied to the wound and secured with the thin adhesive strips. The wound was dressed with the primary nonadhesive dressing, EXU-DRY (Smith+Nephew) and secondary dressings. The patient was instructed to keep the dressing dry and intact. Per protocol, the patient was to return weekly to the outpatient clinic for an additional 4 weeks.  

At 1-week postoperatively, the wound had decreased in size by 40% (24.0 cm²; Figure 2B). The patient returned to the clinic 3 days later as a result of a cellulitis AE; however, the wound had further decreased to 20.1 cm². At 3-weeks postoperatively, the wound measured 16.0 cm² and the cellulitis AE had resolved (Figure 2C). At the end of the 4 weeks of treatment, the wound measured 21.25 cm², with an overall PAR of 47% (Figure 2D).

The purpose of the present study was to prospectively evaluate the clinical outcomes of vCUT plus standard of care (SOC) in the treatment of acute and chronic complex wounds. A vCUT allograft is a commercially available cryopreserved umbilical cord tissue that retains the components and properties inherent to native tissue; however, outcomes of vCUT in a variety of indications have only been evaluated in smaller retrospective case studies.^10,12-14

Generally, very little published data exist regarding effective treatment options for patients with complex wounds. Split-thickness skin grafts (STSGs) are one of the most commonly used procedural techniques when wounds cannot be closed by primary intention. The success of STSGs relies on a well-vascularized wound bed with healthy granulation tissue. Due to the lack of vascularity and paucity of sites with exposed bone, tendon, muscle, or hardware, STSGs are not always a feasible treatment option for complex wounds.¹⁵ 

To address this issue, complex wounds are often pre-treated with negative pressure wound therapy (NPWT). Negative pressure wound therapy is the process by which subatmospheric pressure is either continuously or intermittently applied to the wound through a specialized pump in a close sealed system. This therapy has been shown to promote granulation tissue and tissue perfusion, as well as decrease edema, bacterial colonization, and wound drainage.^16-19

Argenta and Morykwas²⁰ first described prospective clinical outcomes with NPWT in the treatment of 300 acute and chronic wounds. A total of 296 wounds responded favorably to the NPWT treatment, though specific outcomes (eg, time to healing) were not reported. In 2000, DeFranzo et al²¹ evaluated 75 patients with lower extremity complex wounds and found that NPWT decreased edema and, subsequently, the surface area of the wound. Additionally, these wounds presented with healthy granulation tissue and bacterial counts that had significantly decreased. Of the 75 patients, 71 achieved wound closure, with 12 wounds treated by delayed primary closure, 58 with an STSG, and 5 with a flap.²¹ Overall, the literature supports the use of NPWT in the treatment of nonhealing wounds; however, there is limited data from larger, prospective studies that show efficacy in the treatment of complex wounds without the need for additional adjunctive therapy.²²  

In recent years, skin substitute use for difficult-to-heal wounds has become more prevalent in wound care facilities. One such product, BMWD, a bilayered skin replacement system comprised of a porous matrix of cross-linked bovine tendon collagen and glycosaminoglycan and a semi-permeable silicone layer, has been on the market since 2004 (INTEGRA Bilayer Wound Matrix; Integra LifeSciences).²³ 

Iorio et al⁸ performed a retrospective review on the use of BMWD application for lower extremity limb salvage. Patients were classified as either high risk for amputation or low risk for amputation and then further separated into cohorts with and without diabetes for analysis. In low-risk patients with diabetes, 17% progressed to amputation, and 54% of high-risk patients with diabetes progressed to amputation.⁸ In low-risk patients without diabetes, only 3% progressed to amputation. This study⁸ showed positive clinical outcomes for the use of BMWD in the population of low-risk patients without diabetes. The rate of salvage was not improved for high-risk patients with diabetes. Further, patients had to undergo at least 2 surgical procedures. Once revascularization was achieved after intraoperative BMWD application, patients returned to the operating room to receive a skin graft. No closure rates were reported.⁸

Another skin substitute that has been used in the treatment of complex wounds is cryopreserved placental membrane containing viable cells (vCPM). In 2016, Frykberg et al²⁴ described the clinical outcomes of a weekly application of cryopreserved human placental membrane plus SOC in the treatment of chronic complex DFUs. After 16 weeks of treatment, 96.3% of patients achieved 100% granulation, and 59.3% of patients achieved complete wound closure in an average of 9.1 weeks.²⁴ Also in 2016, a clinical effectiveness review²⁵ was conducted for 12 patients who were treated with a weekly application of vCPM plus SOC in the management of complex wounds. All 12 wounds achieved complete wound closure without adjunct interventions such as NPWT, hyperbaric oxygen, or surgery in an average time of 10 weeks.²⁵ 

Similar to vCPM, vCUT retains the components and anti-inflammatory, antimicrobial, anti-fibrotic, and angiogenic properties inherent to fresh placental tissue.^26-29 As such, it was hypothesized that positive clinical outcomes also would be seen utilizing vCUT in the treatment of complex wounds. In the current study, the proportion of patients that achieved 100% granulation was 80%, and 30% of wounds went on to achieve complete closure by the end of the 4-week treatment period.  

In the 2 representative cases, the first patient was able to achieve complete closure of all 3 wounds. Although the second patient did not achieve closure, the patient had a significant reduction in wound size and 100% granulation in only 4 weeks. Closure in 4 weeks would not necessarily be expected in this patient population with larger, complex wounds. 

The main difference between vCUT and other advanced therapies that have been used to treat complex wounds is that these therapies often require additional surgical procedures or therapies after granulation to achieve closure. This is often the case with BMWD usage specifically, as STSGs are often used in conjunction with BMWD after a wound granulates. In these instances, the silicone layer of the BMWD graft needs to be removed, along with any excessive granulation, necrotic tissue, and areas of incomplete take.²³ Following this, an epidermal autograft needs to be harvested and attached to the wound site. This can be problematic, as not every patient is a good candidate for an autograft, and an additional wound donor site is created. Patients with significant comorbidities, such as diabetes and peripheral vascular disease, can have impaired reepithelialization of the initial wound site and donor site.³⁰

A vCUT allograft has the added benefit of not requiring any additional surgical steps, though surgery can be considered if needed. Wound closure is achievable without the use of an autologous graft or other adjunctive therapy in the outpatient setting. This was demonstrated in the previously mentioned 10-patient retrospective case series involving complex wounds with gas gangrene.¹⁰ 

The present study is not without its limitations, with the main one being the small sample size and the lack of a control arm. Additionally, a longer study duration of either 12 weeks or 16 weeks would be needed to accurately assess closure outcomes.

Clinical outcomes of vCUT have been evaluated in smaller, retrospective case studies and reports. The main strength of the present study is its prospective design. The results of this pilot study also show positive outcomes for vCUT plus SOC in the treatment of complex wounds, an area of clinical research in which published data are lacking. 

Authors: Robert F. Mullins, MD¹; Zaheed Hassan, MD¹; Bounthavy Homsombath, MD¹; Shawn Fagan, MD¹; Beretta Craft-Coffman, PA-C¹; Joan Wilson, MSN, MHA, RN²; John G. Rumbaugh, MD²;Molly Saunders, BS³; and Alla Danilkovitch, PhD³ 

Affiliations: ¹JMS Burn Center, Joseph M. Still Research Foundation, Augusta, GA; ²Joseph M. Still Research Foundation; and ³Osiris Therapeutics, Inc, Columbia, MD

Correspondence: Molly Saunders, BS, Sr. Manager, Clinical Operations, Osiris Therapeutics, Inc., Clinical, 7015 Albert Einstein Drive, Columbia, MD 21046; molly.saunders@smith-nephew.com

Disclosure: Ms. Saunders is a current employee of Osiris Therapeutics. Dr. Danilkovitch was a former employee of Osiris Therapeutics. This study was funded by Osiris Therapeutics.