Isolation of fibroblasts for coating of meshes for reconstructive surgery: differences between mesh types

Functionalized Strategies and Mechanisms of the Emerging Mesh for Abdominal Wall Repair and Regeneration

Meshes have been the overwhelmingly popular choice for the repair of abdominal wall defects to retrieve the bodily integrity of musculofascial layer. Broadly, they are classified into synthetic, biological and composite mesh based on their mechanical and biocompatible features. With the development of anatomical repair techniques and the increasing requirements of constructive remodeling, however, none of these options satisfactorily manages the conditional repair. In both preclinical and clinical studies, materials/agents equipped with distinct functions have been characterized and applied to improve mesh-aided repair, with the importance of mesh functionalization being highlighted. However, limited information exists on systemic comparisons of the underlying mechanisms with respect to functionalized strategies, which are fundamental throughout repair and regeneration. Herein, we address this topic and summarize the current literature by subdividing common functions of the mesh into biomechanics-matched, macrophage-mediated, integration-enhanced, anti-infective and antiadhesive characteristics for a comprehensive overview. In particular, we elaborate their effects separately with respect to host response and integration and discuss their respective advances, challenges and future directions toward a clinical alternative. From the vastly different approaches, we provide insight into the mechanisms involved and offer suggestions for personalized modifications of these emerging meshes.

Stress Urinary Incontinence and Pelvic Organ Prolapse: Biologic Graft Materials Revisited

Symptomatic stress urinary incontinence (SUI) and pelvic organ prolapse (POP) refractory to conservative management with pelvic floor muscle training or vaginal pessaries may warrant surgical intervention with different forms of biologic or synthetic material. However, in recent years, several global regulatory agencies have issued health warnings and recalled several mesh products due to an increase in complications such as mesh erosion, infection, chronic pain, and perioperative bleeding. At present, current surgical treatment strategies for SUI and POP are aimed at developing biological graft materials with similar mechanical properties to established synthetic meshes, but with improved tissue integration and minimal host response. This narrative review aims to highlight recent studies related to the development of biomimetic and biologic graft materials as alternatives to traditional synthetic materials for SUI/POP repair in female patients. We also investigate complications and technical limitations associated with synthetic mesh and biological biomaterials in conventional SUI and POP surgery. Our findings demonstrate that newly developed biologic grafts have a lower incidence of adverse events compared to synthetic biomaterials. However there remains a significant disparity between success in preclinical trials and long-term clinical translation. Further characterization on the optimal structural, integrative, and mechanical properties of biological grafts is required before they can be reliably introduced into clinical practice for SUI and POP surgery. Impact statement Our review article aims to outline the clinical history of developments and controversies associated with the use of synthetic mesh materials in the surgical treatment of stress urinary incontinence and pelvic organ prolapse, as well as highlighting recent advancements in the area of biological graft materials and their potential importance in an area that remains an enduring issue for patients and clinicians alike. This article aims to provide a concise summary of previous controversies in the field of urinary incontinence, while evaluating the future of potential biomaterials in this field.

Meshes in a mess: Mesenchymal stem cell-based therapies for soft tissue reinforcement

Surgical meshes are frequently used for the treatment of abdominal hernias, pelvic organ prolapse, and stress urinary incontinence. Though these meshes are designed for tissue reinforcement, many complications have been reported. Both differentiated cell- and mesenchymal stem cell-based therapies have become attractive tools to improve their biocompatibility and tissue integration, minimizing adverse inflammatory reactions. However, current studies are highly heterogeneous, making it difficult to establish comparisons between cell types or cell coating methodologies. Moreover, only a few studies have been performed in clinically relevant animal models, leading to contradictory results. Finally, a thorough understanding of the biological mechanisms of mesenchymal stem cells in the context of foreign body reaction is lacking. This review aims to summarize in vitro and in vivo studies involving the use of differentiated and mesenchymal stem cells in combination with surgical meshes. According to preclinical and clinical studies and considering the therapeutic potential of mesenchymal stem cells, it is expected that these cells will become valuable tools in the treatment of pathologies requiring tissue reinforcement. STATEMENT OF SIGNIFICANCE: The implantation of surgical meshes is the standard procedure to reinforce tissue defects such as hernias. However, an adverse inflammatory response secondary to this implantation is frequently observed, leading to a strong discomfort and chronic pain in the patients. In many cases, an additional surgical intervention is needed to remove the mesh. Both differentiated cell- and stem cell-based therapies have become attractive tools to improve biocompatibility and tissue integration, minimizing adverse inflammatory reactions. However, current studies are incredibly heterogeneous and it is difficult to establish a comparison between cell types or cell coating methodologies. This review aims to summarize in vitro and in vivo studies where differentiated and stem cells have been combined with surgical meshes.

Attachment of Primary Vaginal Fibroblasts to Absorbable and Nonabsorbable Implant Materials Coated With Platelet-Rich Plasma: Potential Application in Pelvic Organ Prolapse Surgery

OBJECTIVES

Pelvic organ prolapse (POP) is a common condition in women. The lifetime risk of undergoing surgery to correct POP is 11%, with 30% recurrence rate. Various types of vaginal implants, absorbable and nonabsorbable, that have been introduced in pelvic floor reconstructive surgeries have numerous serious adverse effects. Platelet-rich plasma (PRP) is an autologous product that accelerates tissue healing and regeneration. We hypothesized that autologous PRP will promote human vaginal fibroblast (HVF) attachment to vaginal implants and increase their healing potential.

METHODS

Vaginal tissue biopsies were collected from postmenopausal patients with POP (n = 10) and asymptomatic control subjects (n = 4) during vaginal hysterectomy or repair. Primary cells were isolated and characterized by immunocytochemistry. Cell attachment and proliferation were compared between POP HVFs and control HVFs (n = 4/group). Twelve weeks after the surgery, blood samples were collected from 6 POP patients to obtain autologous PRP. Two meshes, absorbable (Vicryl) and nonabsorbable (Restorelle), were coated in PRP or control media; autologous POP HVFs (n = 6) were seeded on meshes for 2 hours. Cells attached to the meshes were fixed, stained with DAPI (4,6-diamidino-2-phenylindole dihydrochloride), and counted.

RESULTS

Pelvic organ prolapse HVFs were similar to control HVFs in attachment to different matrix substrates and in proliferation rate. Attachment of POP HVFs to both meshes was significantly increased after coating with PRP versus Dulbecco modified Eagle medium (Vicryl: 9875 vs. 1006 cells/cm, Restorelle: 3724 vs. 649 cells/cm; P < 0.001 for both).

CONCLUSIONS

In vitro, primary POP HVFs show better attachment to implant materials when treated with PRP, which may lead to reduced mesh-related complications in vivo, indicating its great potential for urogynecologic surgeries.

Comparative Characterization of Vaginal Cells Derived From Premenopausal Women With and Without Severe Pelvic Organ Prolapse

BACKGROUND

This study tested a hypothesis that primary human vaginal cells derived from tissue of premenopausal women with severe pelvic organ prolapse (POP-HVCs) would display differential functional characteristics as compared to vaginal cells derived from asymptomatic women with normal pelvic floor support (control-HVCs).

METHODS

Vaginal tissue biopsies were collected from premenopausal patients with POP (n = 8) and asymptomatic controls (n = 7) during vaginal hysterectomy or repair. Primary vaginal cells were isolated by enzymatic digestion and characterized by immunocytochemistry. Cell attachment and proliferation on different matrices (collagen I, collagen II, collagen IV, fibronectin, laminin, tenascin, and vitronectin) were compared between POP-HVCs and control-HVCs. RNA was extracted, and the expression of 84 genes was screened using Human Extracellular Matrix and Adhesion Molecules RT(2) Profiler PCR array. The expression of selected genes was verified by quantitative reverse transcription-polymerase chain reaction.

RESULTS

(1) Control-HVCs attached to collagen IV more efficiently than POP-HVCs; (2) control-HVCs and POP-HVCs show a similar proliferation rate when plated on proNectin and collagen I; (3) when seeded on collagen I, resting POP-HVCs expressed significantly (P < .05) increased transcript levels of collagen VII, multiple matrix metalloproteinases (MMP3, MMP7, MMP10, MMP12, MMP13, and MMP14), integrins (ITGA1, ITGA4, ITGA6, ITGA8, ITGB1, ITGB2, and ITGB3), and cell adhesion molecules as compared to control-HVCs. Collagen XV and tissue inhibitors of MMPs (TIMP1 and TIMP2) as well as genes involved in the biogenesis and maturation of collagen and elastin fibers (LOX, LOXL1-LOXL3, BMP1, and ADAMTS2) were significantly downregulated in POP-HVCs versus control-HVCs (P < .05).

CONCLUSIONS

Resting primary POP-HVCs in vitro show altered cellular characteristics as compared to control-HVCs, which may influence their dynamic responses to external mechanical or hormonal stimuli.

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.

Methodology of fibroblast and mesenchymal stem cell coating of surgical meshes: a pilot analysis

Coating of various synthetic, absorbable, and biologic meshes with mesenchymal stem cells (MSCs) and fibroblasts was analyzed qualitatively and quantitatively. Five hernia meshes-light weight monofilament polypropylene (Soft Mesh), polyester (Parietex-TET), polylactide composite (TIGR), heavy weight monofilament polypropylene (Marlex), and porcine dermal collagen (Strattice)-were coated with three cell lines: human dermal fibroblasts (HFs), rat kidney fibroblasts (NRKs), and rat MSCs. Cell densities were determined at different time points. Samples also underwent histology and transmission electron microscopic (TEM) analyses. It required HFs 3 weeks to cover the entire mesh, while only 2 weeks for NRKs and MSCs to do so. MSCs had no preference for any of the meshes and produced the highest cell densities on Parietex and TIGR. Substrate-preference accounted for the significantly lower fibroblast densities on TIGR than Parietex. Fibroblasts failed to coat Marlex. Strattice, which had the least surface area, generated comparable cell densities to Parietex. Both histology and TEM confirmed cell coating of mesh surface. Various prosthetics can be coated by certain cell strains. Both mesh composition and cell preference dramatically influence the coating process. This methodology provides foundation for novel avenues of modulation of host response to various modern synthetic and biologic meshes.

Comparison of candidate scaffolds for tissue engineering for stress urinary incontinence and pelvic organ prolapse repair

OBJECTIVES

To identify candidate materials which have sufficient potential to be taken forward for an in vivo tissue-engineering approach to restoring the tissue structure of the pelvic floor in women with stress urinary incontinence (SUI) or pelvic organ prolapse (POP).

MATERIALS AND METHODS

Oral mucosal fibroblasts were seeded onto seven different scaffold materials, AlloDerm ( LifeCell Corp., Branchburg, NJ, USA), cadaveric dermis, porcine dermis, polypropylene, sheep forestomach, porcine small intestinal submucosa (SIS) and thermoannealed poly(L) lactic acid (PLA) under both free and restrained conditions. The scaffolds were assessed for: cell attachment using AlamarBlue and 4,6-diamidino-2-phenylindole (DAPI); contraction using serial photographs; and extracellular matrix production using Sirius red staining, immunostaining and scanning electron microscopy. Finally the biomechanical properties of all the scaffolds were assessed.

RESULTS

Of the seven, there were two biodegradable scaffolds, synthetic PLA and natural SIS, which supported good cell attachment and proliferation. Immunostaining confirmed the presence of collagen I, III and elastin which was highest in SIS and PLA. The mechanical properties of PLA were closest to native tissue with an ultimate tensile strength of 0.72 ± 0.18 MPa, ultimate tensile strain 0.53 ± 0.16 and Young's modulus 4.5 ± 2.9 MPa. Scaffold restraint did not have a significant impact on the above properties in the best scaffolds.

CONCLUSION

These data support both PLA and SIS as good candidate materials for use in making a tissue-engineered repair material for SUI or POP.

Tissue engineering as a potential alternative or adjunct to surgical reconstruction in treating pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Cell-based tissue engineering strategies could potentially provide attractive alternatives to surgical reconstruction of native tissue or the use of surgical implants in treating pelvic organ prolapse (POP).

METHODS

Based on a search in PubMed, this review focuses on candidate cell types, scaffolds, and trophic factors used in studies examining cell-based tissue engineering strategies to treat POP, stress urinary incontinence (SUI), and the closely related field of hernias.

RESULTS

In contrast to the field of SUI, the use of cell-based tissue engineering strategies to treat POP are very sparsely explored, and only preclinical studies exist.

CONCLUSION

The available evidence suggests that the use of autologous muscle-derived cells, fibroblasts, or mesenchymal stem cells seeded on biocompatible, degradable, and potentially growth-promoting scaffolds could be an alternative to surgical reconstruction of native tissue or the use of conventional implants in treating POP. However, the vagina is a complex organ with great demands of functionality, and the perfect match of scaffold, cell, and trophic factor has yet to be found and tested in preclinical studies. Important issues such as safety and economy must also be addressed before this approach is ready for clinical studies.

Tissue engineering as a potential alternative or adjunct to surgical reconstruction in treating pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Cell-based tissue engineering strategies could potentially provide attractive alternatives to surgical reconstruction of native tissue or the use of surgical implants in treating pelvic organ prolapse (POP).

METHODS

Based on a search in PubMed, this review focuses on candidate cell types, scaffolds, and trophic factors used in studies examining cell-based tissue engineering strategies to treat POP, stress urinary incontinence (SUI), and the closely related field of hernias.

RESULTS

In contrast to the field of SUI, the use of cell-based tissue engineering strategies to treat POP are very sparsely explored, and only preclinical studies exist.

CONCLUSION

The available evidence suggests that the use of autologous muscle-derived cells, fibroblasts, or mesenchymal stem cells seeded on biocompatible, degradable, and potentially growth-promoting scaffolds could be an alternative to surgical reconstruction of native tissue or the use of conventional implants in treating POP. However, the vagina is a complex organ with great demands of functionality, and the perfect match of scaffold, cell, and trophic factor has yet to be found and tested in preclinical studies. Important issues such as safety and economy must also be addressed before this approach is ready for clinical studies.