Reconstruction of large-size abdominal wall defect using biodegradable poly-p-dioxanone mesh: an experimental canine study

Enabling Proregenerative Medical Devices via Citrate-Based Biomaterials: Transitioning from Inert to Regenerative Biomaterials

Regenerative medicine aims to restore tissue and organ function without the use of prosthetics and permanent implants. However, achieving this goal has been elusive, and the field remains mostly an academic discipline with few products widely used in clinical practice. From a materials science perspective, barriers include the lack of proregenerative biomaterials, a complex regulatory process to demonstrate safety and efficacy, and user adoption challenges. Although biomaterials, particularly biodegradable polymers, can play a major role in regenerative medicine, their suboptimal mechanical and degradation properties often limit their use, and they do not support inherent biological processes that facilitate tissue regeneration. As of 2020, nine synthetic biodegradable polymers used in medical devices are cleared or approved for use in the United States of America. Despite the limitations in the design, production, and marketing of these devices, this small number of biodegradable polymers has dominated the resorbable medical device market for the past 50 years. This perspective will review the history and applications of biodegradable polymers used in medical devices, highlight the need and requirements for regenerative biomaterials, and discuss the path behind the recent successful introduction of citrate-based biomaterials for manufacturing innovative medical products aimed at improving the outcome of musculoskeletal surgeries.

Abdominal wall hernia repair: from prosthetic meshes to smart materials

Hernia reconstruction is one of the most frequently practiced surgical procedures worldwide. Plastic surgery plays a pivotal role in reestablishing desired abdominal wall structure and function without the drawbacks traditionally associated with general surgery as excessive tension, postoperative pain, poor repair outcomes, and frequent recurrence. Surgical meshes have been the preferential choice for abdominal wall hernia repair to achieve the physical integrity and equivalent components of musculofascial layers. Despite the relevant progress in recent years, there are still unsolved challenges in surgical mesh design and complication settlement. This review provides a systemic summary of the hernia surgical mesh development deeply related to abdominal wall hernia pathology and classification. Commercial meshes, the first-generation prosthetic materials, and the most commonly used repair materials in the clinic are described in detail, addressing constrain side effects and rational strategies to establish characteristics of ideal hernia repair meshes. The engineered prosthetics are defined as a transit to the biomimetic smart hernia repair scaffolds with specific advantages and disadvantages, including hydrogel scaffolds, electrospinning membranes, and three-dimensional patches. Lastly, this review critically outlines the future research direction for successful hernia repair solutions by combing state-of-the-art techniques and materials.

A Prospective, Single-Center, Phase I Clinical Trial to Evaluate the Value of Transesophageal Echocardiography in the Closure of Patent Foramen Ovale With a Novel Biodegradable Occluder

Objective

Traditional metal alloy occluders for the closure of patent foramen ovale (PFO) may be associated with some potential complications, and may restrict the trans-septal access to the left atrium for future treatment of left-sided heart disease. Increasing attention has been paid to novel biodegradable occluders (NBOs) to achieve PFO closure. We aimed to evaluate the role of transesophageal echocardiography (TEE) in the diagnostic and anatomical evaluation of PFO, as well as in the Post-procedural assessment after transcatheter closure with a NBO.

Methods

We conducted a prospective, single-center clinical study of 44 patients who were diagnosed with PFO by contrast transthoracic echocardiography (c-TTE) and TEE from June 2019 to June 2020. All patients underwent PFO occlusion with NBO under TTE guidance. Follow-up was performed at 2 days and 3 months after the procedure with TTE, and at 6 months and 1 year after the procedure with c-TTE, TTE, and TEE.

Results

Interventional treatment was successfully performed in all patients. The left and right sides of the occluder device disc were significantly reduced at 3, 6, and 12 months compared to 2 days after the procedure (all P < 0.01), and decreased gradually. The thickness was significantly reduced at 12 months compared to the first three time points (all P < 0.01). Thrombus was found on the surface of the occluder device in three patients (6.4%) at 3 and 6 months after occlusion. At 6 months after procedure, there were 3 (6.8%) cases of extensive residual right-to-left shunt (RLS), 2 (4.5%) cases of moderate shunt, and 7 (15.9%) cases of small shunts. One year after procedure, 2 (4.5%) cases had a extensive residual shunt, 6 (13.6%) cases of small shunts were confirmed to originate from pulmonary veins by TEE, and the PFO-RLS occlusion rate reached 95.5%.

Conclusion

This study demonstrates the feasibility, safety, and effectiveness of NBO for the closure of PFO in humans, with a high rate of complete shunt closure. Accurate TEE assessment of the PFO anatomy before closure with NBO is important to ensure that the procedure remains safe and effective. Furthermore, TEE plays a crucial role in the Post-procedure follow-up.

Regulatory science for hernia mesh: Current status and future perspectives

Regulatory science for medical devices aims to develop new tools, standards and approaches to assess the safety, effectiveness, quality and performance of medical devices. In the field of biomaterials, hernia mesh is a class of implants that have been successfully translated to clinical applications. With a focus on hernia mesh and its regulatory science system, this paper collected and reviewed information on hernia mesh products and biomaterials in both Chinese and American markets. The current development of regulatory science for hernia mesh, including its regulations, standards, guidance documents and classification, and the scientific evaluation of its safety and effectiveness was first reported. Then the research prospect of regulatory science for hernia mesh was discussed. New methods for the preclinical animal study and new tools for the evaluation of the safety and effectiveness of hernia mesh, such as computational modeling, big data platform and evidence-based research, were assessed. By taking the regulatory science of hernia mesh as a case study, this review provided a research basis for developing a regulatory science system of implantable medical devices, furthering the systematic evaluation of the safety and effectiveness of medical devices for better regulatory decision-making. This was the first article reviewing the regulatory science of hernia mesh and biomaterial-based implants. It also proposed and explained the concepts of evidence-based regulatory science and technical review for the first time.

A novel internal abdominal oblique muscle flap to close a major abdominal wall defect

This report describes a novel technique for abdominal wall reconstruction using an internal abdominal oblique muscle flap in an Australian kelpie. En bloc resection of a chondrosarcoma and biopsy scar centred on the 13th rib was performed to include full thickness thoracic wall (12th rib, extending caudally) and lateral abdominal wall (including the vascular pedicle of the external abdominal oblique muscle). The diaphragm was advanced to close the thorax. A flap using the caudal internal abdominal oblique muscle with the base dorsally was elevated and rotated 90° to fill the dorsal defect. The ventral defect was closed using the composite ventral abdominal muscles. The skin was closed primarily. The dog developed a self-resolving seroma. Twelve months postoperatively, the dog was able to engage in agility competitions. A viable muscle flap using the internal abdominal oblique muscle provides a useful alternative to previously described techniques for autogenous closure of a large abdominal wall wound.

Partial replacement of left hemidiaphragm in dogs by either cryopreserved or decellularized heterograft patch

OBJECTIVES

Large diaphragmatic defects are still a challenging issue for reconstruction using either synthetic prosthesis or bioprosthesis. To evaluate the possibility of using diaphragm allograft as a natural bioprosthesis in humans, we conducted a two-group study and compared cryopreserved and decellularized diaphragmatic heterograft patched in a canine model.

METHODS

At the end of organ harvesting from a human donor, the left hemidiaphragm was taken to the laboratory in phosphate-buffered saline solution. The next step was freezing the grafts at -80°C, and preserving them for up to 2 months in Group 1. It was subjected to a detergent-enzymatic method (containing sodium deoxycholate/DNase lavations) of decellularization for 25 cycles in Group 2. Through left thoracotomy in the eighth intercostal space, cryopreserved patches in six dogs and decellularized patches in five dogs replaced the diaphragm. During the follow-up, sonography was done in all animals, but three and two dogs in Group 1 and 2 underwent computed tomography (CT) scan, respectively. The animals were euthanized after 6 months.

RESULTS

There was no mortality. Sonography showed only motion impairment of the patches in all cases. In Group 1, CT scan showed mild atelectasis and scattered infiltration in the left lower lobe, fibrotic bands and minimal fluid collection under the diaphragm. In Group 2, CT scan showed scattered fibrotic bands and mild to moderate elevation of the left hemidiaphragm. There was no evidence of gross disruption and complete healing of the suture line. Necropsy in both groups showed patches were completely replaced with a dense fibrous tissue. In Group 1, focal calcification was noticeable in every case and foreign body-type granulomas were clearly seen all over the grafted tissue. Histology in Group 2 animals showed less inflammatory cell infiltration and scattered foreign body granulomas in comparison with the cryopreserved patch graft.

CONCLUSIONS

The gross healing process in the decellularized heterograft is similar to the cryopreserved diaphragm but with fewer inflammatory cells and foreign body granulomas on histology. Both of them can be used instead of bioprostheses with regard to the fact that the decellularized patch technique is more complex and expensive. It is recommended to compare them with commercial bioprostheses.

Surgical mesh for ventral incisional hernia repairs: Understanding mesh design

Surgical mesh has become an indispensable tool in hernia repair to improve outcomes and reduce costs; however, efforts are constantly being undertaken in mesh development to overcome postoperative complications. Common complications include infection, pain, adhesions, mesh extrusion and hernia recurrence. Reducing the complications of mesh implantation is of utmost importance given that hernias occur in hundreds of thousands of patients per year in the United States. In the present review, the authors present the different types of hernia meshes, discuss the key properties of mesh design, and demonstrate how each design element affects performance and complications. The present article will provide a basis for surgeons to understand which mesh to choose for patient care and why, and will explain the important technological aspects that will continue to evolve over the ensuing years.

Surgical mesh for ventral incisional hernia repairs: Understanding mesh design

Surgical mesh has become an indispensable tool in hernia repair to improve outcomes and reduce costs; however, efforts are constantly being undertaken in mesh development to overcome postoperative complications. Common complications include infection, pain, adhesions, mesh extrusion and hernia recurrence. Reducing the complications of mesh implantation is of utmost importance given that hernias occur in hundreds of thousands of patients per year in the United States. In the present review, the authors present the different types of hernia meshes, discuss the key properties of mesh design, and demonstrate how each design element affects performance and complications. The present article will provide a basis for surgeons to understand which mesh to choose for patient care and why, and will explain the important technological aspects that will continue to evolve over the ensuing years.

Emerging Trends in Abdominal Wall Reinforcement: Bringing Bio-Functionality to Meshes

Abdominal wall hernia is a recurrent issue world-wide and requires the implantation of over 1 million meshes per year. Because permanent meshes such as polypropylene and polyester are not free of complications after implantation, many mesh modifications and new functionalities have been investigated over the last decade. Indeed, mesh optimization is the focus of intense development and the biomaterials utilized are now envisioned as being bioactive substrates that trigger various physiological processes in order to prevent complications and to promote tissue integration. In this context, it is of paramount interest to review the most relevant bio-functionalities being brought to new meshes and to open new avenues for the innovative development of the next generation of meshes with enhanced properties for functional abdominal wall hernia repair.