Ovine forestomach matrix biomaterial is a broad spectrum inhibitor of matrix metalloproteinases and neutrophil elastase

Updates on Recent Clinical Assessment of Commercial Chronic Wound Care Products

Impaired wound healing after trauma, disorders, and surgeries impact millions of people globally every year. Dysregulation in orchestrated healing mechanisms and underlying medical complications make chronic wound management extremely challenging. Besides standard-of-care treatments including broad spectrum antibiotics and wound-debridement, novel adjuvant therapies are clinically tested and commercialized. These include topical agents, skin substitutes, growth factor delivery, and stem cell therapies. With a goal to overcome factors playing pivotal role in delayed wound healing, researchers are exploring novel approaches to elicit desirable healing outcomes in chronic wounds. Although recent innovations in wound care products, therapies, and devices are extensively reviewed in past, a comprehensive review summarizing their clinical outcomes is surprisingly lacking. Herein, this work reviews the commercially available wound care products and their performance in clinical trials to provide a statistically comprehensive understanding of their safety and efficacy. The performance and suitability of various commercial wound care platforms, including xenogeneic and allogenic products, wound care devices, and novel biomaterials, are discussed for chronic wounds. The current clinical evaluation will provide a comprehensive understanding of the benefits and drawbacks of the most-recent approaches and will enable researchers and healthcare providers to develop next-generation technologies for chronic wound management.

Ovine Forestomach Matrix in the Surgical Management of Complex Volumetric Soft Tissue Defects: A Retrospective Pilot Case Series

Background

Volumetric soft tissue loss is an urgent surgical issue and can frequently lead to suboptimal outcomes for patients due to significant soft tissue loss, compromised vital structures, and contamination. Ovine forestomach matrix (OFM) has demonstrated clinical success in the surgical management of soft tissue defects, especially in contaminated fields, and provides an effective option for immediate coverage of exposed vital structures before definitive closure.

Methods

This retrospective pilot case series (n = 13 defects) evaluated the clinical effectiveness of OFM (graft and/or particulate formats) in the surgical management of contaminated volumetric soft tissue defects. Patients presented with significant soft tissue loss, often with exposed viscera, tendon, bone, or muscle, and were treated with OFM as part of their inpatient surgical management. All patients had at least 1 significant comorbidity with the potential to complicate their healing trajectory. The primary study endpoint was time to 100% granulation tissue coverage (days), and the secondary endpoint was any device-related postoperative complications.

Results

A total of 13 volumetric soft tissue defects were evaluated in 10 patients who underwent surgical reconstruction. Mean defect age was 3.5 ± 5.6 weeks, and mean area was 217.3 ± 77.9 cm2. Most defects had exposed structures (85%), and all defects were Centers for Disease Control and Prevention grade 2 or higher. Mean time to 100% granulation tissue formation was 23.4 ± 9.2 days, with a median product application of 1.0. Staged reconstruction was used in 7 of 13 defects, with the remainder (6 of 13) left to heal via secondary intention using standard wound care protocols. There were no major postoperative infections or adverse events (mean follow-up, 7.4 ± 2.4 weeks.).

Conclusions

This retrospective pilot case series builds on a growing body of evidence that OFM can be utilized to facilitate the formation of functional, well-vascularized soft tissue in large contaminated volumetric soft tissue defects.

Surgical management of perianal fistula using an ovine forestomach matrix implant

PURPOSE

Invasive surgical management of cryptoglandular perianal fistulas (PF) is challenging because of high recurrence rates and the potential for injury to the sphincter complex. In the present technical note, we introduce a minimally invasive treatment for PF using a perianal fistula implant (PAFI) comprising ovine forestomach matrix (OFM).

METHODS

This retrospective observational case series highlights 14 patients who had undergone a PAFI procedure at a single center between 2020 and 2023. During the procedure, previously deployed setons were removed and tracts were de-epithelialized with curettage. OFM was rehydrated, rolled, passed through the debrided tract, and secured in place at both openings with absorbable suture. Primary outcome was fistula healing at 8 weeks, and secondary outcomes included recurrence or postoperative adverse events.

RESULTS

Fourteen patients underwent PAFI using OFM with a mean follow-up period of 37.6 ± 20.1 weeks. In follow-up, 64% (n = 9/14) had complete healing at 8 weeks and all remained healed, except one at last follow-up visit. Two patients underwent a second PAFI procedure and were healed with no recurrence at the last follow-up visit. Of all patients that healed during the study period (n = 11), the median time to healing was 3.6 (IQR 2.9-6.0) weeks. No postprocedural infections nor adverse events were noted.

CONCLUSIONS

The minimally invasive OFM-based PAFI technique for PF treatment was demonstrated to be a safe and feasible option for patients with trans-sphincteric PF of cryptoglandular origin.

Recent advances in decellularized biomaterials for wound healing

The skin is one of the most essential organs in the human body, interacting with the external environment and shielding the body from diseases and excessive water loss. Thus, the loss of the integrity of large portions of the skin due to injury and illness may lead to significant disabilities and even death. Decellularized biomaterials derived from the extracellular matrix of tissues and organs are natural biomaterials with large quantities of bioactive macromolecules and peptides, which possess excellent physical structures and sophisticated biomolecules, and thus, promote wound healing and skin regeneration. Here, we highlighted the applications of decellularized materials in wound repair. First, the wound-healing process was reviewed. Second, we elucidated the mechanisms of several extracellular matrix constitutes in facilitating wound healing. Third, the major categories of decellularized materials in the treatment of cutaneous wounds in numerous preclinical models and over decades of clinical practice were elaborated. Finally, we discussed the current hurdles in the field and anticipated the future challenges and novel avenues for research on decellularized biomaterials-based wound treatment.

Membranous Extracellular Matrix-Based Scaffolds for Skin Wound Healing

Membranous extracellular matrix (ECM)-based scaffolds are one of the most promising biomaterials for skin wound healing, some of which, such as acellular dermal matrix, small intestinal submucosa, and amniotic membrane, have been clinically applied to treat chronic wounds with acceptable outcomes. Nevertheless, the wide clinical applications are always hindered by the poor mechanical properties, the uncontrollable degradation, and other factors after implantation. To highlight the feasible strategies to overcome the limitations, in this review, we first outline the current clinical use of traditional membranous ECM scaffolds for skin wound healing and briefly introduce the possible repair mechanisms; then, we discuss their potential limitations and further summarize recent advances in the scaffold modification and fabrication technologies that have been applied to engineer new ECM-based membranes. With the development of scaffold modification approaches, nanotechnology and material manufacturing techniques, various types of advanced ECM-based membranes have been reported in the literature. Importantly, they possess much better properties for skin wound healing, and would become promising candidates for future clinical translation.

Fabrication of collagen with polyhexamethylene biguanide: A potential scaffold for infected wounds

Bacterial infection remains a great challenge in wound healing, especially in chronic wounds. Multidrug-resistant organisms are increasing in acute and chronic wound infections, which compromise the chance of therapeutics. Resistance to conventional antibiotics has created an urge to study new approach/system that can effectively control wound infection and enhance healing. Wound cover/dressing must exhibit biocompatibility and effectiveness in reducing bioburden at the wound site. Collagen, a natural biopolymer, possesses advantages over synthetic and other natural materials due to its unique biological properties. It can act as an excellent wound dressing and controlled drug delivery system. Currently, antiseptic agents such as silver, iodine, and polyhexamethylene biguanide (PHMB)-incorporated scaffolds have become widely accepted in chronic wound healing. In this study, PHMB-incorporated collagen scaffold has been prepared and characterized using Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), and differential scanning calorimetry (DSC), which showed retention of collagen nativity and integration of PHMB. The scanning electron microscopy (SEM) analysis revealed the porous structures of scaffolds. The cytotoxicity analysis showed PHMB is nontoxic at the concentration of 0.01% (wt/wt). The agar diffusion test and bacterial adhesion study demonstrated the effectiveness of PHMB-incorporated collagen scaffold against both gram positive and negative strains. This study concludes that PHMB-incorporated collagen scaffold could have the potential for infected wound healing.

Retrospective real-world comparative effectiveness of ovine forestomach matrix and collagen/ORC in the treatment of diabetic foot ulcers

The retrospective pragmatic real‐world data (RWD) study compared the healing outcomes of diabetic foot ulcers (DFUs) treated with either ovine forestomach matrix (OFM) (n = 1150) or collagen/oxidised regenerated cellulose (ORC) (n = 1072) in out‐patient wound care centres. Median time to wound closure was significantly (P = .0015) faster in the OFM group (14.6 ± 0.5 weeks) relative to the collagen/ORC group (16.4 ± 0.7). A sub‐group analysis was performed to understand the relative efficacy in DFUs requiring longer periods of treatment and showed that DFUs treated with OFM healed up to 5.3 weeks faster in these challenging wounds. The percentage of wounds closed at 36 weeks was significantly improved in OFM treated DFUs relative to the collagen/ORC. A Cox proportional hazards analysis showed OFM‐treated wounds had a 18% greater probability of healing versus wounds managed with collagen/ORC, and the probability increased to 21% when the analysis was adjusted for multiple variables. This study represents the first large retrospective RWD analysis comparing OFM and collagen/ORC and supports the clinical efficacy of OFM in the treatment of DFUs.

Surgical reconstruction of pilonidal sinus disease with concomitant extracellular matrix graft placement: a case series

BACKGROUND

Pilonidal sinus disease (PSD) is a chronic inflammatory disease affecting the soft tissue of the sacrococcygeal region and remains a challenging disease for clinicians to treat. The optimal treatment for PSD remains controversial and recent reports describe several different surgical approaches offering different benefits. Approximately 40% of initial incision and drainage cases require subsequent surgery. Due to high recurrence rates and postoperative complications, a more complex revision surgery involving a flap reconstruction may be required. We hypothesised that the combination of an extracellular matrix (ECM) graft with tissue flap reconstruction may decrease the postoperative complications and recurrence rates for PSD.

METHOD

We report a retrospective case series using a surgical flap reconstruction with concomitant implantation of an ovine forestomach ECM graft under a fasciocutaneous flap with an off-midline closure for recurrent PSD, where previously surgical intervention had failed due to wound dehiscence and/or recurrent disease.

RESULTS

The case series included six patients. After three weeks, all patients except one were fully healed, and the sixth was fully healed by week 4; all wounds remained fully healed at 12 weeks. All patients achieved good cosmesis and were able to return to normal function without any residual symptoms.

CONCLUSION

This pilot case series explored augmenting a flap reconstruction for complex PSD with advanced ECM graft materials, demonstrating that it may improve outcomes and minimise typical complications seen in flap closure, such as inflammation, infection, haematoma/seroma and hypoperfusion. Although the study had a limited number of participants, long-term outcomes were promising and suggest that further studies are warranted.

Wound dressings: curbing inflammation in chronic wound healing

Chronic wounds represent an economic burden to healthcare systems worldwide and a societal burden to patients, deeply impacting their quality of life. The incidence of recalcitrant wounds has been steadily increasing since the population more susceptible, the elderly and diabetic, are rapidly growing. Chronic wounds are characterised by a delayed wound healing process that takes longer to heal under standard of care than acute (i.e. healthy) wounds. Two of the most common problems associated with chronic wounds are inflammation and infection, with the latter usually exacerbating the former. With this in mind, researchers and wound care companies have developed and marketed a wide variety of wound dressings presenting different compositions but all aimed at promoting healing. This makes it harder for physicians to choose the correct therapy, especially given a lack of public quantitative data to support the manufacturers’ claims. This review aims at giving a brief introduction to the clinical need for chronic wound dressings, focusing on inflammation and evaluating how bio-derived and synthetic dressings may control excess inflammation and promote healing.

Extracellular matrix graft for reconstruction over exposed structures: a pilot case series

OBJECTIVE

Soft tissue defects, especially those involving exposed vital structures, present a reconstructive challenge because poor vascularity of such defects typically makes immediate skin grafting unviable. Where flap procedures are inappropriate or not possible, dermal matrices represent an alternative reconstructive option for defects with denuded vital structures. With dermal matrices becoming increasingly available and technologically advanced, we evaluated an ovine-derived extracellular matrix graft in the reconstruction of complex soft tissue defects involving exposed vital structures.

METHOD

Six cases of soft tissue defects exhibiting denuded vital structures underwent reconstruction using an ovine forestomach matrix graft as a dermal matrix. Grafts were fixed directly into defects for immediate coverage and subsequently temporised defects via granulation tissue formation for later skin graft or secondary closure. Defect granulation and epithelialisation were monitored until closure and the final aesthetic and functional outcomes were evaluated.

RESULTS

Complete healing was achieved in all cases, with defect granulation becoming observable within one to two weeks and complete granulation occurring within one to six weeks. Granulation tissue resulting from the graft was suitable for skin grafting, with 100% take of skin grafts after one week and complete re-epithelialisation in two to three weeks in the four cases that received a skin graft. Good cosmetic, functional and patient satisfaction outcomes were achieved in all cases.

CONCLUSION

The present series demonstrates our initial use of an extracellular matrix-based dermal matrix in reconstructing defects with exposed vital structures. While such dermal matrices do not supersede or replace flap procedures, they represent an alternative option on the reconstructive ladder in cases where flap procedures are not appropriate or possible.

Prospective Multicenter Evaluation of an Advanced Extracellular Matrix for Wound Management

OBJECTIVE

To evaluate an advanced extracellular matrix made of ovine forestomach matrix (OFM) for healing a variety of wound types.

METHODS

Participants were enrolled from inpatient, outpatient, and home healthcare settings. The OFM was used to treat all wounds and applied to the wound bed every 3 to 7 days until closure.

RESULTS

Researchers enrolled 29 participants with 33 wounds. Average time to wound closure was 8.2 weeks, the percentage of wounds that reduced in size by 50% or more at 4 weeks was 64%, the average wound area reduction at 4 weeks was 66%, and 73% of wounds had closed at 12 weeks. No adverse effects were observed.

CONCLUSIONS

This represents the first Canadian evaluation of OFM for the treatment of wounds, and the positive healing outcomes observed could support more widespread adoption of this matrix.

Decellularized xenografts in regenerative medicine: From processing to clinical application

Decellularized xenografts are an inherent component of regenerative medicine. Their preserved structure, mechanical integrity and biofunctional composition have well established them in reparative medicine for a diverse range of clinical indications. Nonetheless, their performance is highly influenced by their source (ie species, age, tissue) and processing (ie decellularization, crosslinking, sterilization and preservation), which govern their final characteristics and determine their success or failure for a specific clinical target. In this review, we provide an overview of the different sources and processing methods used in decellularized xenografts fabrication and discuss their effect on the clinical performance of commercially available decellularized xenografts.

Case Report: Surgical Closure of Chronic Soft Tissue Defects Using Extracellular Matrix Graft Augmented Tissue Flaps

Chronic soft tissue defects are notoriously difficult to heal. Surgical reconstruction of chronic defects using tissue flaps is a routine approach for closure of challenging chronic defects. Due to the poor tissue quality of chronic defects and associated inflammation, infection and impaired blood supply the success of flap closure is marred by reported complication rates of 25-58%. Extracellular matrix (ECM)-based graft materials are commonly used for resolving chronic wounds and in plastic and reconstructive procedures to create a scaffold for tissue regeneration. We hypothesized combination use of ECM grafts with tissue flaps in a single-stage surgical procedure would reduce complications and improve outcomes in the closure of chronic soft tissue defects. We report a case series (n = 9) of chronic soft tissue defect reconstruction using this modified procedure of ECM graft augmented flap closure. Defects included pressure injuries and surgical dehiscence and ranged in wound age from 5 months to 7 years. Successful uncomplicated healing was achieved in six defects. Post-operative complications (dehiscence) occurred in two defects, however, these healed via secondary intention without additional surgical intervention. All healed defects exhibited acceptable cosmesis and "normal" function, with 100% patient satisfaction. Augmentation of tissue flaps with ECM graft materials in this modified single-stage procedure may improve outcomes and minimize typical complications encountered in flap closure of chronic defects attributed to inflammation, infection, hypoperfusion, and dead space.

Extracellular matrix graft for the surgical management of Hurley stage III hidradenitis suppurativa: a pilot case series

Objective:

Surgical management of Hurley stage III hidradenitis suppurativa (HS) typically involves the excision of diseased tissue and subsequent reconstruction, potentially leading to complications or recurrence of the disease. This pilot case series sought to evaluate a decellularised ovine forestomach matrix (OFM) extracellular matrix (ECM) graft for soft tissue regeneration as part of surgical reconstruction of stage III HS of the axilla.

Method:

The prospective pilot case series involved six participants and a total of eight defects. The ECM graft was used either as a dermal substitute for a staged reconstruction (n=3 defects) or as an implant under a fasciocutaneous flap (n=5 defects) following wide excision of the diseased tissue.

Results:

In all cases complete healing was achieved, with no major surgical complications. When used as a dermal substitute the OFM graft was completely granulated within 2–4 weeks, with defects closing by secondary intention or following placement of a split-thickness skin graft. When used as an implant beneath a fasciocutaneous flap, healing of the surgical sites was observed after 1–3 months. At the long-term follow-up (3–12 months), all participants had excellent range of motion and none had reported disease recurrences.

Conclusion:

This pilot case series explored the implementation of an ECM graft as part of the surgical management of axilla Hurley stage III HS. Although the study had a limited number of participants, long-term outcomes were promising and suggest further studies are warranted.

Effect of Native Type I Collagen with Polyhexamethylene Biguanide Antimicrobial on Wounds: Interim Registry Results

BACKGROUND

Biofilm can impair wound healing by maintaining an elevated, but ineffective, inflammatory state. This article describes interim results from the prospective RESPOND postmarketing registry evaluating the use of a native type 1, porcine collagen matrix with the embedded antimicrobial polyhexamethylene biguanide (PCMP) in the management of chronic wounds.

METHODS

Adults ≥18 years of age with ≥1 appropriate wound were eligible for inclusion. Data that were final on January 26, 2018 were included in this analysis. At week 0, wounds were cleaned, debrided, and prepared as necessary and PCMP was applied, with a dressing to fix it in place. Patients received standard wound care plus PCMP weekly, up to 24 weeks, at the investigator's discretion. At each visit, wounds were assessed for area and quality of granulation tissue.

RESULTS

Most common wound types (N = 63) were venous ulcers (28.6%), trauma and lacerations (22.2%), postsurgical open wounds (15.9%), pressure injuries (12.7%), and diabetic ulcers (9.5%). Median baseline wound area was 6.5 cm2; mean wound duration at baseline was 4 months. Of the 63 wounds, 43 (68.3%) achieved complete wound closure, 41 of 43 (95.3%) closed after PCMP treatment, and 2 of 43 (4.7%) after bridging to other modalities and surgical closure. Twelve out of 63 wounds were bridged to other modalities after PCMP treatment. Mean time to closure for PCMP wounds was 5.0 weeks.

CONCLUSIONS

PCMP appears to be a useful adjunct for treating various wound types. PCMP use should be considered when managing chronic or acute wounds.

Ionic silver functionalized ovine forestomach matrix - a non-cytotoxic antimicrobial biomaterial for tissue regeneration applications

BACKGROUND

Antimicrobial technologies, including silver-containing medical devices, are increasingly utilized in clinical regimens to mitigate risks of microbial colonization. Silver-functionalized resorbable biomaterials for use in wound management and tissue regeneration applications have a narrow therapeutic index where antimicrobial effectiveness may be outweighed by adverse cytotoxicity. We examined the effects of ionic silver functionalization of an extracellular matrix (ECM) biomaterial derived from ovine forestomach (OFM-Ag) in terms of material properties, antimicrobial effectiveness and cytotoxicity profile.

METHODS

Material properties of OFM-Ag were assessed by via biochemical analysis, microscopy, atomic absorption spectroscopy (AAS) and differential scanning calorimetry. The silver release profile of OFM-Ag was profiled by AAS and antimicrobial effectiveness testing utilized to determine the minimum effective concentration of silver in OFM-Ag in addition to the antimicrobial spectrum and wear time. Biofilm prevention properties of OFM-Ag in comparison to silver containing collagen dressing materials was quantified via in vitro crystal violet assay using a polymicrobial model. Toxicity of ionic silver, OFM-Ag and silver containing collagen dressing materials was assessed toward mammalian fibroblasts using elution cytoxicity testing.

RESULTS

OFM-Ag retained the native ECM compositional and structural characteristic of non-silver functionalized ECM material while imparting broad spectrum antimicrobial effectiveness toward 11 clinically relevant microbial species including fungi and drug resistant strains, maintaining effectiveness over a wear time duration of 7-days. OFM-Ag demonstrated significant prevention of polymicrobial biofilm formation compared to non-antimicrobial and silver-containing collagen dressing materials. Where silver-containing collagen dressing materials exhibited cytotoxic effects toward mammalian fibroblasts, OFM-Ag was determined to be non-cytotoxic, silver elution studies indicated sustained retention of silver in OFM-Ag as a possible mechanism for the attenuated cytotoxicity.

CONCLUSIONS

This work demonstrates ECM biomaterials may be functionalized with silver to favourably shift the balance between detrimental cytotoxic potential and beneficial antimicrobial effects, while preserving the ECM structure and function of utility in tissue regeneration applications.

Use of Native Type I Collagen Matrix Plus Polyhexamethylene Biguanide for Chronic Wound Treatment

Background:

Chronic wounds represent a significant financial burden to the healthcare system and a quality-of-life burden to patients. Many chronic wounds have elevated bioburden in the form of biofilm, which has been associated with delayed wound healing. This study examined the use of a native type I collagen matrix with the antimicrobial polyhexamethylene biguanide (PCMP) in the management of bioburden and treatment of chronic, nonhealing wounds over 12 weeks.

Methods:

A prospective case series of PCMP enrolled adults ≥18 years old with a nonhealing wound. At week 0, the wound was prepared by sharp or mechanical debridement. Patients received standard wound care plus PCMP applications at week 0 and then weekly up to week 12 at the investigator’s discretion. Dressings were applied over PCMP to fix it in place. At each visit, wounds were assessed for the extent of healing and signs of wound infection.

Results:

Of the 41 wounds studied, 44% were pressure ulcers, 22% were surgical wounds, 12% were venous ulcers, 10% were diabetic ulcers, and 12% were another type. The median (interquartile range) baseline wound area was 7.2 (14.9) cm², and the mean wound duration was 103 weeks. Of the 41 wounds, 73% demonstrated a reduction in wound area at 12 weeks, and 37% achieved complete wound closure, with a mean time of 6.7 weeks to complete closure.

Conclusion:

PCMP treatment appeared to positively impact the course of wound healing in a variety of complex, chronic wounds that were unresponsive to prior treatment.

Advances in addressing full-thickness skin defects: a review of dermal and epidermal substitutes

full-thickness skin defects remain a reconstructive challenge. Novel regenerative modalities can aid in addressing these defects. A literature review of currently available dermal and epidermal regenerates was performed. The mechanism and application for each skin substitute was analyzed to provide a guide for these modalities. Available epidermal substitutes include autografts and allografts and may be cultured or noncultured. Dermal regenerate templates exist in biologic and synthetic varieties that differ in the source animal and processing. Epidermal and dermal skin substitutes are promising adjunctive tools for addressing certain soft tissue defects and have improved outcomes in reconstructive procedures. The following article provides a comprehensive review of the biologic materials available and the types of complex wounds amenable to their use.

A hydroxamic acid–methacrylated collagen conjugate for the modulation of inflammation-related MMP upregulation

The selective covalent coupling of hydroxamic acid functions on to methacrylated type I collagen led to UV-cured networks with inherent MMP-modulating capability and enhanced proteolytic stability.

Leg ulcer treatment outcomes with new ovine collagen extracellular matrix dressing: a retrospective case series

The purpose of this study was to describe the rate of closure observed in venous leg ulcers during treatment with ovine collagen extracellular matrix dressings and compression. Fourteen patients with 23 wounds were retrospectively evaluated with respect to healing rates, time to closure, and weekly facility charge fees.

Current Status and Future of Skin Substitutes for Chronic Wound Healing

Chronic wounds, including diabetic ulcers, pressure ulcers, venous ulcers, and arterial insufficiency ulcers, are both difficult and expensive to treat. Conventional wound care may sometimes lead to suboptimal wound healing and significant morbidity and mortality for patients. The use of skin substitutes provides an alternative therapy showing superior efficacy and, in some cases, similar cost-effectiveness compared to traditional treatments. This review discusses the different types of currently available commercial skin substitutes for use in chronic wounds as well as the paucity of strong evidence supporting their use. It then delves into the limitations of these skin substitutes and examines the most recent research targeting these limitations.

Ovine-Based Collagen Matrix Dressing: Next-Generation Collagen Dressing for Wound Care

Significance: Broad-spectrum metalloproteinase (MMP) reduction along with inherent aspects of an extracellular matrix (ECM) dressing can bring about improved wound healing outcomes and shorter treatment duration. Initial reports of clinical effectiveness of a new ovine-based collagen extracellular matrix (CECM) dressing demonstrate benefits in chronic wound healing. Recent Advances: CECM dressings are processed differently than oxidized regenerated cellulose/collagen dressings. CECM dressings consist primarily of collagens I and III arranged as native fibers that retain the three-dimensional architecture present in tissue ECM. As such, ovine-based ECM dressings represent a new generation of collagen dressings capable of impacting a broad spectrum of MMP excess known to be present in chronic wounds. Critical Issues: While MMPs are essential in normal healing, elevated presence of MMPs has been linked to wound failure. Collagen has been shown to reduce levels of MMPs, acting as a sacrificial substrate for excessive proteases in a chronic wound. Preserving collagen dressings in a more native state enhances bioactivity in terms of the ability to affect the chronic wound environment. Clinical observation and assessment may not be sufficient to identify a wound with elevated protease activity that can break down ECM, affect wound fibroblasts, and impair growth factor response. Future Directions: Collagen dressings that target broad-spectrum excessive MMP levels and can be applied early in the course of care may positively impact healing rates in difficult wounds. Next-generation collagen dressings offer broader MMP reduction capacity while providing a provisional dermal matrix or ECM.

Challenges in the Treatment of Chronic Wounds

Significance: Chronic wounds include, but are not limited, to diabetic foot ulcers, venous leg ulcers, and pressure ulcers. They are a challenge to wound care professionals and consume a great deal of healthcare resources around the globe. This review discusses the pathophysiology of complex chronic wounds and the means and modalities currently available to achieve healing in such patients. Recent Advances: Although often difficult to treat, an understanding of the underlying pathophysiology and specific attention toward managing these perturbations can often lead to successful healing. Critical Issues: Overcoming the factors that contribute to delayed healing are key components of a comprehensive approach to wound care and present the primary challenges to the treatment of chronic wounds. When wounds fail to achieve sufficient healing after 4 weeks of standard care, reassessment of underlying pathology and consideration of the need for advanced therapeutic agents should be undertaken. However, selection of an appropriate therapy is often not evidence based. Future Directions: Basic tenets of care need to be routinely followed, and a systematic evaluation of patients and their wounds will also facilitate appropriate care. Underlying pathologies, which result in the failure of these wounds to heal, differ among various types of chronic wounds. A better understanding of the differences between various types of chronic wounds at the molecular and cellular levels should improve our treatment approaches, leading to better healing rates, and facilitate the development of new more effective therapies. More evidence for the efficacy of current and future advanced wound therapies is required for their appropriate use.