A Comparative Analysis in Treatment of Full-Thickness Wounds: NPWT Combined With Type-I Collagen Based Advanced Skin Substitute Versus NPWT Alone
Phase: NA
Conditions: Full Thickness Skin Defects, Ulcer
Sponsor: Adichunchanagiri Institute of Medical Sciences, B G Nagara

Title: Treatment of Full-Thickness Wounds: NPWT Combined with Type-I 
Collagen Based Advanced Skin Substitute Versus NPWT Alone 
 
 
NCT No: NCT06873867 
 
 
Date: November 09, 2025 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

INTRODUCTION 
Full-thickness wounds, which extend through the dermis into the underlying subcutaneous 
tissue or deeper structures, remain a formidable challenge in reconstructive and wound care 
practice. These wounds may arise from trauma, surgical dehiscence, pressure injuries, or 
chronic ulceration, and are often complicated by infection, vascular insufficiency, and 
comorbidities such as diabetes and peripheral vascular disease. They affect millions of patients 
worldwide and impose substantial economic burden on healthcare systems [1, 2]. They are a 
growing concern in healthcare due to their prolonged healing time, high recurrence, and 
associated morbidity [3, 4]. These wounds often demonstrate delayed healing and increased 
risk of complications including infection, chronic inflammation, and impaired tissue 
regeneration [5, 6]. Without optimal management, these wounds fail to heal through the 
conventional stages of wound repair, functional impairment, increased risk of limb loss, poor 
cosmetic results and high healthcare costs. The complex pathophysiology of wound healing 
involves intricate interactions between cellular components, growth factors, extracellular 
matrix proteins, and vascular elements, necessitating comprehensive therapeutic approaches 
to optimize clinical outcomes [7]. 
Negative Pressure Wound Therapy (NPWT) has emerged as an effective modality to 
accelerate wound healing by removing excess exudate, enhancing perfusion, promoting 
granulation tissue formation and maintains an optimal wound environment, and thus is a 
cornerstone in treatment of complex wounds [8, 9, 10]. By applying controlled sub-
atmospheric pressure, NPWT reduces interstitial edema, increases local blood flow, removes 
exudate, and stimulates granulation tissue formation. The application of controlled negative 
pressure creates a conducive environment for cellular proliferation and angiogenesis, 
facilitating the wound healing cascade [11, 12]. Despite its advantages, NPWT alone may not 
suffice for extensive tissue regeneration and achieve rapid epithelialization, especially in 
large or complex wounds where the extracellular matrix (ECM) and vascular supply has been 
significantly compromised [13].  
The integration of biological skin substitutes in wound healing has emerged as a promising 
adjunctive therapy to enhance wound healing outcomes [14, 15]. High Purity Type-I Collagen 
(HPTC) skin substitutes, such as Helicoll®, provide a bioactive scaffold that mimics native 
ECM, facilitating cellular migration, angiogenesis, keratinocyte proliferation and growth 
factor delivery. Helicoll® is an acellular dermal replacement product made of high purity 
(>97%) Type-I Collagen that provides a framework promoting blood vessel regeneration and 
biologic cell migration [16]. It is derived from bovine sources but processed to remove 

antigenic components. Helicoll® undergoes a patented treatment process for purification, 
making it least immunogenic and highly biocompatible [17]. 
These bioengineered constructs offer several advantages including biocompatibility, 
biodegradability, and offer optimal bio-integration with host tissue while promoting natural 
healing processes [18, 19]. Recent RCTs have established its efficacy in chronic wound 
healing, including diabetic foot ulcers and venous leg ulcers [16, 20, 21]. Narayan et al. 
demonstrated that HPTC achieved significantly greater wound closure compared to 
dehydrated human amnion/chorion membrane (dHACM) in diabetic foot ulcers [16]. 
Similarly, an RCT in venous leg ulcers showed faster healing and better granulation quality 
with HPTC than dHACM [20]. Another dual-country RCT involving 55 patients reported 
consistent superiority of HPTC across different patient populations and healthcare settings 
[22]. These studies have shown superior healing rates, reduced healing time, and improved 
tissue quality compared to standard care approaches.  
While these studies establish the role of HPTC in chronic ulcer management, the potential 
synergistic effect of combining HPTC with NPWT in full-thickness wounds has not been 
extensively studied. The rationale for combining NPWT with high-purity type-I collagen-
based skin substitutes lies in their complementary mechanisms of action. Theoretically, NPWT 
could optimize the wound bed and vascular environment (mechanical environment), while 
HPTC provides the structural and biochemical support (biological framework) for accelerated 
tissue regeneration. This combination may result in faster and more complete healing than 
NPWT alone, addressing both the macroscopic and microscopic aspects of wound healing, 
potentially leading to superior clinical outcomes [12, 13, 20, 21, 23]. 
The present study aims to compare the clinical outcomes of NPWT combined with HPTC 
skin substitute versus NPWT alone in patients with full-thickness wounds, using a 
randomized controlled design, to provide robust evidence for clinical decision-making in 
advanced wound care. Our hypothesis is that the combination therapy will result in 
significantly greater wound area reduction, faster closure, improved scar quality, and better 
patient-reported pain outcomes, without increasing adverse events. 
 
 
 
 
 
 

MATERIALS AND METHODS 
This was a prospective, randomized, open-label, parallel-group clinical trial conducted at the 
Department of Plastic, Reconstructive, and Aesthetic Surgery, Adichunchanagiri Institute of 
Medical Sciences (AIMS), Karnataka, India. The study compared the efficacy of Negative 
Pressure Wound Therapy (NPWT) combined with High Purity Type-I Collagen (HPTC) skin 
substitute versus NPWT alone in the management of full-thickness wounds. Patient 
recruitment occurred between March 2025, and July 2025. The anticipated follow-up 
continued until August 2025, with each participant observed for a total of seven weeks (six 
weeks of intervention plus one-week follow-up). The trial was registered prospectively with 
ClinicalTrials.gov (ID: NCT06873867) and approved by the Institutional Ethics Committee 
(Approval No: AIMS/IEC/013/2025). The study adhered to the principles of the Declaration 
of Helsinki and Good Clinical Practice guidelines. All participants provided written informed 
consent prior to enrollment after comprehensive explanation of study procedures, risks, and 
benefits. Patient confidentiality was maintained throughout the study period. 
Patients aged 18-80 years with full-thickness wounds (wound depth extending through 
dermis into subcutaneous tissue), including traumatic, post-surgical dehiscence, burns ulcers, 
pressure ulcers, DFUs, or VLUs, wound size >20 cm2 and <75 cm2, with adequate vascular 
supply to the wound site, ability to comply with treatment protocol and follow-up visits, and 
provided written informed consent were eligible.  
Exclusion criteria included active infection or osteomyelitis requiring systemic antibiotics, 
active malignancy at wound site, immunosuppression, uncontrolled diabetes (HbA1c > 9%), 
on systemic corticosteroids, patients on anticoagulation therapy with INR >3.0 used advanced 
wound care products within the last 30 days, autoimmune or connective tissue disorders or 
allergy to bovine collagen. 
 
Sample Size - Sample size calculation was based on the primary outcome of wound area 
reduction. Assuming a mean difference of 30% in wound area reduction between groups, with 
a standard deviation of 20%, power of 80%, and alpha of 0.05, a minimum of 47 patients per 
group was required. Accounting for 10% dropout rate, at 52 patients per group, with a total 
of 104 patients were recruited. This calculation was informed by effect sizes reported in 
previous HPTC RCTs in diabetic foot, venous leg and pressure ulcers, which demonstrated 
mean differences of 10–15% in wound healing outcomes. [6,7]. 
 

Randomization and Blinding - Participants were randomized 1:1 into two treatment groups 
using a computer-generated randomization sequence with block sizes of 4, 6, and 8. Patients 
were assigned to either: - Group A: NPWT + HPTC or Group B: NPWT alone. 
Randomization was stratified by wound etiology. Allocation concealment was maintained 
using sequentially numbered, opaque, sealed envelopes prepared by a research assistant not 
involved in patient care or outcome assessment. Due to the nature of the intervention, 
complete blinding was not feasible; however, outcome assessors, pathologists, and data 
analysts were blinded to treatment allocation. 
 
Intervention Protocol  
Group A (NPWT + HPTC) - The wound was first debrided to remove necrotic tissue and 
ensure a viable wound bed. A sheet of High Purity Type-I Collagen skin substitute 
(Helicoll®) was applied to completely cover the wound surface. This was followed by a non-
adherent porous dressing layer. NPWT was then applied using polyurethane foam at ~125 
mmHg intermittent pressure (10 minutes on, 2 minutes off) for 5–7 days. The dressing was 
changed as per SOC thereafter, with repeat application of HPTC and NPWT as needed.  
Group B (NPWT alone) - Following debridement, a non-adherent porous dressing was 
applied directly over the wound. NPWT was then initiated with the same parameters 
(polyurethane foam, ~125 mmHg, intermittent mode) and followed by SOC dressing. NPWT 
was reapplied if required. 
All patients received standardized wound care including sharp debridement as needed to 
remove non-viable tissue, infection control with topical antimicrobials when indicated, 
pressure redistribution and offloading as appropriate, nutritional assessment and optimization, 
glycemic control for diabetic patients, compression therapy for venous ulcers and pressure 
offloading for wounds when appropriate. Patient education on wound care was given. 
 
Outcome Measures  
The primary outcome of the study was percentage wound area reduction from week 1 
through week 6 plus 1 week follow up, measured via digital photography. Measurements 
were performed by trained personnel blinded to treatment allocation. 
Secondary outcomes included time to complete wound closure (in days) within 7 weeks, 
proportion of patients achieving complete closure by week 7, histological vascularity 
infiltration, between baseline (Day 0) and Day 5 biopsies, mean number of applications of the 
skin substitute required, incidence of adverse events (infection, allergic reaction, bleeding, 

maceration), pain score change using a 0–10 Visual Analog Scale (VAS) from baseline to 
week 6, and scar quality assessed at week 7 using the Manchester Scar Scale (MSS).  
Complete wound closure is defined as 100% epithelialization. Histopathological assessment 
included taking punch biopsies (2 mm) from the wound edge at baseline and day 5 post-
intervention under local anesthesia (2% lidocaine without epinephrine). Fixation in 10% 
neutral buffered formalin for 24 hours, processing through graded alcohol and paraffin 
embedding, and serial sectioning at 4 μm thickness was done. Samples were processed using 
standard histological techniques and stained with hematoxylin and eosin (H&E), Masson's 
trichrome, CD31 immunohistochemistry, and α-SMA immunohistochemistry. Assessment 
parameters included vascular infiltration (0-3 scale), neo-epithelialization (0-3 scale), 
fibroblast activity (0-3 scale), capillary density (vessels per mm²), inflammatory response (0-
3 scale) and collagen deposition (0-3 scale) (Table 1).  
Quality of Life Assessment using EQ-5D-5L (EuroQol 5-Dimension 5-Level) [25] 
questionnaire, a standardized and widely used instrument for assessing health-related quality 
of life (HRQoL). Developed by the EuroQol Group [25], it provides a simple, generic 
measure applicable to a wide range of diseases and health conditions. The tool evaluates five 
key dimensions of health - mobility, self-care, usual activities, pain/discomfort and 
anxiety/depression. Each dimension is rated on five levels of severity - no problems, slight 
problems, moderate problems, severe problems and extreme problems or inability. These 
combinations describe a respondent’s health state, which can be converted into a single 
summary index score (ranging from less than 0, indicating health states worse than death, to 
1.0, representing full health) using country-specific value sets derived from general 
population preferences. In addition, the EQ-5D-5L [25] includes a Visual Analogue Scale 
(EQ-VAS) [25], a 0-100 scale on which patients rate their overall health (0 = worst 
imaginable health, 100 = best imaginable health). The EQ-5D-5L questionnaire was used in 
its validated Kannada Version 1.1 format, obtained directly from the EuroQol Group under 
non-commercial registration (ID: 78665). The tool was administered in interviewer-assisted 
digital format to ensure accurate comprehension by all participants.  
Scar quality was assessed using Vancouver Scar Scale evaluating vascularity, pigmentation, 
pliability and height/thickness with total score ranging from 0 to 13 (lesser the score better 
the scar) (Table 2). 
 
 
 

Table 1: Histological parameters evaluated in the ulcer bed at baseline and 
on day five of application 
Parameter 
Measurement tool 
Criteria 
Score 
Vascular 
infiltration 
Assessed by counting 
new blood vessels (0–3 
scale) 
Minimal vascular ingrowth 
(<5 vessels/HPF) 
0 
Mild infiltration (5–10 
vessels/HPF) 
1 
Moderate infiltration (11–20 
vessels/HPF) 
2 
Abundant infiltration (>20 
vessels/HPF) 
3 
Neo-
epithelialization 
Measured as epithelial 
migration distance from 
wound edge (0–3 scale) 
No epithelial migration 
0 
Minimal migration (<25% 
wound coverage) 
1 
Moderate migration (25–75% 
coverage) 
2 
Extensive migration (>75% 
coverage) 
3 
Fibroblast activity 
Quantified by counting α-
SMA positive fibroblasts 
per HPF and assessment 
of fibroblast morphology 
(0–3 scale) 
Sparse, inactive fibroblasts 
0 
Moderate cellularity, minimal 
matrix production 
1 
High cellularity, active-matrix 
synthesis 
2 
Very high activity with 
extensive matrix deposition 
3 
Capillary density Evaluated using CD31 staining, counted as vessels per mm² of tissue 
Inflammatory 
response 
Graded semi-
quantitatively (0–3 scale) 
Minimal inflammatory 
infiltrate 
0 
Mild chronic inflammation 
1 
Moderate mixed inflammation 
2 
Severe acute inflammation 
3 
Collagen 
deposition 
Assessed using Masson’s 
trichrome staining (0–3 
scale) 
Minimal collagen matrix 
0 
Loose, immature collagen 
1 
Moderate organized collagen 
2 
Dense, mature collagen 
architecture 
3 
 
 
 
 
 

Table 2: Vancouver Scar Scale 
Parameter 
Score 
Vascularity 
0–3 
Normal  
0 
Pink 
1 
Red 
2 
Purple 
3 
Pigmentation 
0–2 
Normal (matches surrounding 
skin) 
0 
Hypopigmentation 
1 
Hyperpigmentation 
2 
Pliability 
0–5 
Normal 
0 
Supple (flexible with minimal 
resistance) 
1 
Yielding (gives way to pressure) 
2 
Firm (resists movement) 
3 
Banding / rope-like tissue (may 
blanch on extension) 
4 
Contracture (permanent 
shortening producing deformity) 
5 
Height / Thickness 
0–3 
Flat / normal 
0 
< 2 mm 
1 
2–5 mm 
2 
> 5 mm 
3 

Parameter 
Score 
Total Scar Score (Higher scores 
indicate greater scar severity) 
0-13 
 
 
Data Collection and Measurement 
Wound photographs were obtained using standardized digital photography with 
measurement grids. Standardized wound assessments were performed including digital 
photography, wound measurements using validated techniques, and clinical evaluations. 
Wound area was calculated by tracing the wound margin onto a sterile transparent film and 
photographing with a scale reference. Histological evaluation was performed on wound 
biopsies with stains as mentioned in Table 1. Pain assessments (Visual Analogue Scale) and 
quality of life score were completed at baseline, every week thereafter for 7 weeks. 
 
Statistical Analysis  
All data were analyzed using SPSS version 26.0 (IBM Corporation, Armonk, NY). Continuous 
variables were expressed as mean ± standard deviation and compared using independent t-
tests or Mann–Whitney U tests where appropriate. Categorical variables were expressed as 
frequencies and percentages, compared using chi-square or Fisher’s exact test. Repeated 
measures ANOVA was employed for longitudinal outcome analysis. Time-to-event outcomes 
were analyzed using Kaplan-Meier survival analysis with log-rank tests.