Comparison of Antibiotic-Coated versus Uncoated Porcine Dermal Matrix:

Advances, challenges, and future directions in the clinical translation of ECM biomaterials for regenerative medicine applications

Extracellular Matrix (ECM) scaffolds and biomaterials have been widely used for decades across a variety of diverse clinical applications and have been implanted in millions of patients worldwide. ECM-based biomaterials have been especially successful in soft tissue repair applications but their utility in other clinical applications such as for regeneration of bone or neural tissue is less well understood. The beneficial healing outcome with the use of ECM biomaterials is the result of their biocompatibility, their biophysical properties and their ability to modify cell behavior after injury. As a consequence of successful clinical outcomes, there has been motivation for the development of next-generation formulations of ECM materials ranging from hydrogels, bioinks, powders, to whole organ or tissue scaffolds. The continued development of novel ECM formulations as well as active research interest in these materials ensures a wealth of possibilities for future clinical translation and innovation in regenerative medicine. The clinical translation of next generation formulations ECM scaffolds faces predictable challenges such as manufacturing, manageable regulatory pathways, surgical implantation, and the cost required to address these challenges. The current status of ECM-based biomaterials, including clinical translation, novel formulations and therapies currently under development, and the challenges that limit clinical translation of ECM biomaterials are reviewed herein.

The Effect of 3-Dimensional-Printed Sequential Dual Drug-Releasing Patch on the Capsule Formation Around the Silicone Implant in a Rat Model

BACKGROUND

Implant-based breast reconstruction is associated with increased risk of early infection and late-stage capsular contracture.

OBJECTIVES

We evaluated the feasibility of a dual drug-releasing patch that enabled the controlled delivery of antibiotics and immunosuppressants in a temporally and spatially appropriate manner to the implant site.

METHODS

The efficacy of a dual drug-releasing patch, which was 3-dimensional-printed (3D-printed) with tissue-derived biomaterial ink, was evaluated in rats with silicone implants. The groups included implant only (n = 10); implant plus bacterial inoculation (n = 14); implant, bacterial inoculation, and patch loaded with gentamycin placed on the ventral side of the implant (n = 10), and implant, bacterial inoculation, and patch loaded with gentamycin and triamcinolone acetonide (n = 9). Histologic and immunohistochemical analyses were performed 8 weeks after implantation.

RESULTS

The 2 drugs were sequentially released from the dual drug-releasing patch and exhibited different release profiles. Compared to the animals with bacterial inoculation, those with the antibiotic-only and the dual drug-releasing patch exhibited thinner capsules and lower myofibroblast activity and inflammation, indicating better tissue integration and less foreign body response. These effects were more pronounced with the dual drug-releasing patch than with the antibiotic-only patch.

CONCLUSIONS

The 3D-printed dual drug-releasing patch effectively reduced inflammation and capsule formation in a rat model of silicone breast reconstruction. The beneficial effect of the dual drug-releasing patch was better than that of the antibiotic-only patch, indicating its therapeutic potential as a novel approach to preventing capsular contracture while reducing concerns of systemic side effects.

Antimicrobial Meshes for Hernia Repair: Current Progress and Perspectives

Recent advances in the development of biomaterials have given rise to new options for surgery. New-generation medical devices can control chemical breakdown and resorption, prevent post-operative adhesion, and stimulate tissue regeneration. For the fabrication of medical devices, numerous biomaterials can be employed, including non-degradable biomaterials (silicone, polypropylene, expanded polytetrafluoroethylene) or biodegradable polymers, including implants and three-dimensional scaffolds for tissue engineering, which require particular physicochemical and biological properties. Based on the combination of new generation technologies and cell-based therapies, the biocompatible and bioactive properties of some of these medical products can lead to progress in the repair of injured or harmed tissue and in tissue regeneration. An important aspect in the use of these prosthetic devices is the associated infection risk, due to the medical complications and socio-economic impact. This paper provides the latest achievements in the field of antimicrobial surgical meshes for hernia repair and discusses the perspectives in the development of these innovative biomaterials.

Poly-4-hydroxybutyrate (Phasix™) mesh onlay in complex abdominal wall repair

BACKGROUND

Poly-4-hydroxybutyric acid (P4HB, Phasix™) is a biosynthetic polymer that degrades by hydrolysis that can be woven into a mesh for use in soft tissue reinforcement. Herein, we describe our initial experience performing complex abdominal wall repair (CAWR) utilizing component separation and P4HB mesh as onlay reinforcement.

METHODS

All patients undergoing CAWR between June 2014 and May 2017 were followed prospectively for postoperative outcomes. Only those patients who underwent components separation with primary repair of the fascial edges followed by onlay of P4HB mesh were included in this study.

RESULTS

105 patients (52 male, 53 female; mean age 59.2 years, range 22-84) met inclusion criteria. Mean BMI was 29.1 (range 16-48); 52% patients had prior attempted hernia repair, most with multiple medical comorbidities (71% of patients with ASA 3 or greater). 30% of cases were not clean at the time of repair (CDC class 2 or greater). Median follow-up was 36 months (range 9-63). Eighteen patients (17%) developed a hernia recurrence ranging from 2 to 36 months postoperatively. Five (5%) patients developed a localized superficial infection treated with antibiotics, three (2.8%) required re-operation for non-healing wounds, and six (6%) patients developed seroma.

CONCLUSIONS

These data demonstrate a relatively low rate of hernia recurrence, seroma, and other common complications of CAWR in a highly morbid patient population. Importantly, the rate of mesh infection was low and no patients required complete mesh removal, even when placed into a contaminated or infected surgical field.

Contamination of hybrid hernia meshes compared to bioresorbable Phasix™ Mesh in a rabbit subcutaneous implant inoculation model

Background

Hybrid hernia meshes combine biological tissue-derived extracellular matrix with permanent or resorbable synthetic. The objective of this study was to evaluate hybrid meshes (Gore® Synecor, Zenapro™, Ovitex™ 1S Reinforced Bioscaffold Permanent, and Ovitex™ 1S Reinforced Bioscaffold Resorbable) compared to non-hybrid, bioresorbable synthetic mesh (Phasix™ Mesh) in a rabbit bacterial inoculation model.

Materials and methods

Subcutaneous pockets were bilaterally created in male, New Zealand White rabbits (n = 25). Circular meshes (3.8 cm diameter) were implanted and inoculated with 1 × 10⁶ colony forming units (CFU) of clinically-isolated methicillin-resistant Staphylococcus aureus (MRSA). A given animal received a single mesh type. Seven days post-inoculation, animals were euthanized and white material and microbial colonization were assessed by abscess scoring and CFU quantification, respectively. Non-parametric Kruskal-Wallis with Dunn's post-hoc tests compared results for different meshes.

Results

Phasix™ Mesh and Synecor exhibited significantly lower abscess scores than Zenapro™, Ovitex™ 1S Permanent, and Ovitex™ 1S Resorbable (p < 0.05). All pocket swabs for Zenapro™ and Ovitex™ meshes were positive for MRSA (100%), with 20% of Synecor and 0% Phasix™ Mesh. Microbial colonization was significantly lower for Phasix™ Mesh (0 CFU) relative to Zenapro™ (6.73 × 10⁷ CFU (median)), Ovitex™ 1S Permanent (7.87 × 10⁷ CFU) and Ovitex™ 1S Resorbable (1.45 × 10⁸ CFU), and for Synecor (0 CFU) relative to both Ovitex™ meshes. Phasix™ Mesh was the only device with no detectable abscess or microbial colonization.

Conclusion

Phasix™ Mesh demonstrated no detectable abscess or microbial colonization at 7-days post-implantation and inoculation, in contrast with four hybrid meshes, which all demonstrated colonization in a rabbit bacterial inoculation model.

Characterization of host response, resorption, and strength properties, and performance in the presence of bacteria for fully absorbable biomaterials for soft tissue repair

PURPOSE

The objective was to evaluate the host response, resorption, and strength properties, and to assess the performance in the presence of bacteria for Phasix™ Mesh (Phasix™) and Gore® Bio-A® Tissue Reinforcement (Bio-A®) in preclinical models.

METHODS

In a rat model, one mesh (2 × 2 cm) was implanted subcutaneously in n = 60 rats. Animals were euthanized after 2, 4, 8, 12, 16, or 24 weeks (n = 5/mesh/time point), and implant sites were assessed for host inflammatory response and overall fibrotic repair thickness. In a rabbit model, meshes (3.8 cm diameter) were bilaterally implanted in subcutaneous pockets in n = 20 rabbits (n = 10 rabbits/mesh) and inoculated with 108 CFU clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). One mesh type was implanted per animal. Animals were euthanized after 7 days, and implants were assessed for abscess formation, bacterial colonization, and mechanical strength.

RESULTS

In the rat study, Phasix™ and Bio-A® exhibited similar biocompatibility, although Bio-A® demonstrated a significantly greater inflammatory response at 4 weeks compared to Phasix™ (p < 0.01). Morphometric analysis demonstrated rapid resorption of Bio-A® implants with initially thicker repair sites at 2, 4, 8, and 12 weeks (p < 0.0001), which transitioned to significantly thinner sites compared to Phasix™ at 16 and 24 weeks (p < 0.0001). In the rabbit bacterial inoculation study, Phasix™ exhibited significantly lower abscess score (p < 0.001) and bacterial colonization (p < 0.01), with significantly greater mechanical strength than Bio-A® (p < 0.001).

CONCLUSIONS

Host response, resorption, repair thickness, strength, and bacterial colonization suggest a more stable and favorable outcome for monofilament, macroporous devices such as Phasix™ relative to multifilament, microporous devices such as Bio-A® over time.

Minimizing Skin Scarring through Biomaterial Design

Wound healing continues to be a major burden to patients, though research in the field has expanded significantly. Due to an aging population and increasing comorbid conditions, the cost of chronic wounds is expected to increase for patients and the U.S. healthcare system alike. With this knowledge, the number of engineered products to facilitate wound healing has also increased dramatically, with some already in clinical use. In this review, the major biomaterials used to facilitate skin wound healing will be examined, with particular attention allocated to the science behind their development. Experimental therapies will also be evaluated.