Safety, tolerability and efficacy of topical human fibroblasts in patients with chronic refractory wounds (two-part study)

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What is this study about?

The trial focuses on refractory wounds, which are skin sores that have not healed despite usual medical care. The treatment being tested is a skin‑applied patch called FB-Plus that contains human fibroblasts. Fibroblasts are normal cells that help build and repair the tissue that makes up skin, and in this product they come from a donor (this is called allogeneic fibroblasts).

The purpose of the study is to see whether a single application of the patch is safe and well tolerated and, in the second part, whether it can help wounds get smaller or heal completely. The first phase will compare two different strengths of the patch, looking for any side effects. The dose that appears safest and most promising will be used in the later phase to test how well the wound improves.

Participants will receive one patch during each phase and will be followed for a period of time to check for any reactions, changes in vital signs, and overall comfort. In the expansion phase, researchers will also measure the size of the wound, pain levels, and how satisfied they are with the result, using simple scales and questionnaires that are easy to understand.

1 initial visit and enrollment

you attend the first study visit after signing the consent form. this visit marks the start of the trial.

a series of baseline measurements are taken, including a physical examination, vital signs (blood pressure, heart rate), a 12‑lead electrocardiogram (ecg), and blood and urine tests.

2 baseline wound assessment

the size and depth of the chronic refractory wound are measured and recorded.

questionnaires about wound pain and quality of life are completed to establish a starting point for later comparison.

3 application of the study product

a fb-plus patch containing human fibroblasts is placed on the wound. the patch is a topical (skin‑surface) preparation that does not require injection.

only one patch is applied during the entire trial. in the dose‑escalation part of the study the patch may contain a low or a higher strength of fibroblasts; in the later expansion part a single strength is used.

4 post‑application monitoring

you are observed for any immediate reactions after the patch is applied.

scheduled follow‑up visits occur during the next four weeks to check the wound and to record any adverse events (any new symptoms or problems). typical visit days include day 3, day 7, day 14, and day 28, but exact timing follows the study schedule.

5 safety assessments during follow‑up

at each visit the study team repeats the physical examination, vital signs, and may repeat blood and urine tests to monitor safety.

the investigator rates overall tolerability of the patch on a 5‑point scale, ranging from “very well tolerated” to “not tolerated at all.”

6 efficacy evaluations

the wound size is measured again to determine any reduction in area.

the wound bed score (a measure of how the wound surface looks) and the pain level using a visual analogue scale are recorded.

the investigator also rates overall satisfaction with the product’s effect on a 5‑point scale.

7 final study visit

at the last visit, all safety and efficacy data collected during the trial are reviewed.

the final wound assessment determines whether the wound has healed, reduced by at least 50%, or shows any other change.

the study concludes for you after this final evaluation.

Who Can Join the Study?

Sign a written informed consent form, which means you agree to take part after understanding what will happen.
Be 18 years old or older at the time of screening.
Have a BMI (body‑mass index, a measure of weight relative to height) between 18.5 and 40, and weigh at least 45 kg.
Show a negative result on a pregnancy test (if applicable).
If you are a female, you must either be unable to become pregnant (for example, surgically sterilized or post‑menopausal with no periods for at least 2 years and appropriate hormone levels) or, if you could become pregnant, agree to avoid sex or use a highly reliable birth‑control method during the study.
If you are a male with a female partner who could become pregnant, you must agree to use a highly reliable birth‑control method.
Have one single ulcer (a sore) on the lower leg that has been present for at least 3 months, has not healed with usual treatments, has an infection grade of 0‑1 according to the WIfI system (a way doctors rate wound infection), and measures between 5 and 40 cm² in surface area.
Be scheduled for surgical debridement (removal of dead tissue) of the ulcer and have this procedure done no more than 24 hours before the study treatment is applied.
Be willing and able to follow all study visits, schedules, and procedures.

Who Cannot Join the Study?

Having recent serious illnesses of the heart, lungs, kidneys, liver, hormones, metabolism, stomach/intestines, blood, bleeding problems, nerves, or mental health that could make participation unsafe.
Being judged by the study doctor as unlikely to follow the study rules or to cooperate with the study procedures.
Having a history of alcohol, medication, or drug abuse within the past two years.
Having an acute ulcer (a new sore that started less than three months ago).
Having poor nutrition, shown by a body weight too low for height (BMI under 18.5), low protein level in blood (serum albumin under 2.4 g/dL), or losing more than 10 % of ideal weight in the last three months.
Taking other medicines or having other diseases that could seriously affect wound healing, such as steroids (corticosteroids), pain relievers that reduce inflammation (NSAIDs), drugs that suppress the immune system (immunosuppressive), or cancer‑killing drugs (cytotoxic agents), unless these have been stable for at least three months and will not be changed during the study.
Being pregnant or breast‑feeding, as shown by a positive urine pregnancy test (β‑HCG).
Not being willing, or having a partner who is not willing, to use reliable birth control from the first dose until the study ends.
Using other experimental medicines or having taken part in another clinical trial within three months before joining this study.
Having a known allergy to collagen, streptomycin, penicillin, or any product that comes from cows (bovine origin).

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Centro Ricerche Cliniche Di Verona S.r.l.	Verona	Italy

Trial status

Country	Status	Recruitment Start
Italy	Not yet recruiting	15.02.2026

Trial locations

Investigated drugs:

HUMAN FIBROBLASTS

FB-Plus is a topical patch that contains human fibroblast cells taken from a donor. The patch is placed on the skin over a chronic wound. The fibroblasts are a type of cell that helps produce the proteins and structure needed for skin to heal. In this study, a single application of the patch is used to see if it is safe, well‑tolerated, and can improve healing of wounds that have not responded to other treatments. The trial first tests two different strengths of the patch to find the best one, and then uses that chosen strength in a larger group of patients to check how well it works.

Refractory wounds – Refractory wounds are skin injuries that do not show normal healing within the expected timeframe, typically remaining open for weeks or months. They often persist despite standard wound care and may be linked to factors such as reduced blood flow, infection, or repeated trauma. Over time, the wound edges can become hardened and the surrounding tissue may stay inflamed. The wound size may stay the same or gradually increase, and the surface can develop a thickened base with limited new tissue growth. Patients may notice ongoing pain, drainage, or odor as the wound remains unhealed.

Trial ID:

2025-522647-17-00

Protocol code:

FB Plus-01-23

Trial Phase:

Phase I and Phase II (Integrated) – First administration to humans

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Safety, tolerability and efficacy of topical human fibroblasts in patients with chronic refractory wounds (two-part study)

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