Porous poly-l-lactide-co-ɛ-caprolactone scaffold: a novel biomaterial for vaginal tissue engineering

Promoting cell proliferation and collagen production with ascorbic acid 2-phosphate-releasing poly(l-lactide-co-ε-caprolactone) membranes for treating pelvic organ prolapse

Pelvic organ prolapse (POP) afflicts millions of women globally. In POP, the weakened support of the pelvic floor results in the descent of pelvic organs into the vagina, causing a feeling of bulging, problems in urination, defaecation and/or sexual function. However, the existing surgical repair methods for relapsed POP remain insufficient, highlighting the urgent need for more effective alternatives. Collagen is an essential component in pelvic floor tissues, providing structural support, and its production is controlled by ascorbic acid. Therefore, we investigated novel ascorbic acid 2-phosphate (A2P)-releasing poly(l-lactide-co-ε-caprolactone) (PLCLA2P) membranes in vitro to promote cell proliferation and extracellular matrix protein production to strengthen the natural support of the pelvic fascia for POP applications. We analysed the mechanical properties and the impact of PLCLA2P on cellular responses through cell culture analysis using human vaginal fibroblasts (hVFs) and human adipose-derived stem/stromal cells (hASCs) compared to PLCL. In addition, the A2P release from PLCLA2P membranes was assessed in vitro. The PLCLA2P demonstrated slightly lower tensile strength (2.2 ± 0.4 MPa) compared to PLCL (3.7 ± 0.6 MPa) for the first 4 weeks in vitro. The A2P was most rapidly released during the first 48 h of in vitro incubation. Our findings demonstrated significantly increased proliferation and collagen production of both hVFs and hASCs on A2P-releasing PLCLA2P compared to PLCL. In addition, extracellular collagen Type I fibres were detected in hVFs, suggesting enhanced collagen maturation on PLCLA2P. Moreover, increased extracellular matrix protein expression was detected on PLCLA2P in both hVFs and hASCs compared to plain PLCL. In conclusion, these findings highlight the potential of PLCLA2P as a promising candidate for promoting tissue regeneration in applications aimed for POP tissue engineering applications.

Ascorbic Acid 2-Phosphate Releasing Supercritically Foamed Porous Poly-L-Lactide-Co-ε-Caprolactone Scaffold Enhances the Collagen Production of Human Vaginal Stromal Cells: A New Approach for Vaginal Tissue Engineering

BACKGROUND

The reconstructive surgery of vaginal defects is highly demanding and susceptible to complications, especially in larger defects requiring nonvaginal tissue grafts. Thus, tissue engineering-based solutions could provide a potential approach to the reconstruction of vaginal defects.

METHODS

Here, we evaluated a novel porous ascorbic acid 2-phosphate (A2P)-releasing supercritical carbon dioxide foamed poly-L-lactide-co-ε-caprolactone (scPLCLA2P) scaffold for vaginal reconstruction with vaginal epithelial (EC) and stromal (SC) cells. The viability, proliferation, and phenotype of ECs and SCs were evaluated in monocultures and in cocultures on d 1, d 7 and d 14. Furthermore, the collagen production of SCs on scPLCLA2P was compared to that on scPLCL without A2P on d 14.

RESULTS

Both ECs and SCs maintained their viability on the scPLCLA2P scaffold in mono- and coculture conditions, and the cells maintained their typical morphology during the 14-d culture period. Most importantly, the scPLCLA2P scaffolds supported the collagen production of SCs superior to plain scPLCL based on total collagen amount, collagen I and III gene expression results and collagen immunostaining results.

CONCLUSION

This is the first study evaluating the effect of A2P on vaginal tissue engineering, and the results are highly encouraging, indicating that scPLCLA2P has potential as a scaffold for vaginal tissue engineering.

Ascorbic Acid 2-Phosphate-Releasing Supercritical Carbon Dioxide-Foamed Poly(L-Lactide-Co-epsilon-Caprolactone) Scaffolds Support Urothelial Cell Growth and Enhance Human Adipose-Derived Stromal Cell Proliferation and Collagen Production

Tissue engineering can provide a novel approach for the reconstruction of large urethral defects, which currently lacks optimal repair methods. Cell-seeded scaffolds aim to prevent urethral stricture and scarring, as effective urothelium and stromal tissue regeneration is important in urethral repair. In this study, the aim was to evaluate the effect of the novel porous ascorbic acid 2-phosphate (A2P)-releasing supercritical carbon dioxide-foamed poly(L-lactide-co-ε-caprolactone) (PLCL) scaffolds (scPLCLA2P) on the viability, proliferation, phenotype maintenance, and collagen production of human urothelial cell (hUC) and human adipose-derived stromal cell (hASC) mono- and cocultures. The scPLCLA2P scaffold supported hUC growth and phenotype both in monoculture and in coculture. In monocultures, the proliferation and collagen production of hASCs were significantly increased on the scPLCLA2P compared to scPLCL scaffolds without A2P, on which the hASCs formed nonproliferating cell clusters. Our findings suggest the A2P-releasing scPLCLA2P to be a promising material for urethral tissue engineering.

Tissue Engineering Neovagina for Vaginoplasty in Mayer-Rokitansky-Küster-Hauser Syndrome and Gender Dysphoria Patients: A Systematic Review

Background: Vaginoplasty is a surgical solution to multiple disorders, including Mayer-Rokitansky-Küster-Hauser syndrome and male-to-female gender dysphoria. Using nonvaginal tissues for these reconstructions is associated with many complications, and autologous vaginal tissue may not be sufficient. The potential of tissue engineering for vaginoplasty was studied through a systematic bibliography search. Cell types, biomaterials, and signaling factors were analyzed by investigating advantages, disadvantages, complications, and research quantity. Search Methods: A systematic search was performed in Medline, EMBASE, Web of Science, and Scopus until March 8, 2022. Term combinations for tissue engineering, guided tissue regeneration, regenerative medicine, and tissue scaffold were applied, together with vaginoplasty and neovagina. The snowball method was performed on references and a Google Scholar search on the first 200 hits. Original research articles on human and/or animal subjects that met the inclusion (reconstruction of vaginal tissue and tissue engineering method) and no exclusion criteria (not available as full text; written in foreign language; nonoriginal study article; genital surgery other than neovaginal reconstruction; and vaginal reconstruction with autologous or allogenic tissue without tissue engineering or scaffold) were assessed. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist, the Newcastle-Ottawa Scale, and the Gold Standard Publication Checklist were used to evaluate article quality and bias. Outcomes: A total of 31 out of 1569 articles were included. Data extraction was based on cell origin and type, biomaterial nature and composition, host species, number of hosts and controls, neovaginal size, replacement fraction, and signaling factors. An overview of used tissue engineering methods for neovaginal formation was created, showing high variance of cell types, biomaterials, and signaling factors and the same topics were rarely covered multiple times. Autologous vaginal cells and extracellular matrix-based biomaterials showed preferential properties, and stem cells carry potential. However, quality confirmation of orthotopic cell-seeded acellular vaginal matrix by clinical trials is needed as well as exploration of signaling factors for vaginoplasty. Impact statement General article quality was weak to sufficient due to unreported cofounders and incomplete animal study descriptions. Article quality and heterogenicity made identification of optimal cell types, biomaterials, or signaling factors unreliable. However, trends showed that autologous cells prevent complications and compatibility issues such as healthy cell destruction, whereas stem cells prevent cross talk (interference of signaling pathways by signals from other cell types) and rejection (but need confirmation testing beyond animal trials). Natural (orthotopic) extracellular matrix biomaterials have great preferential properties that encourage future research, and signaling factors for vascularization are important for tissue engineering of full-sized neovagina.

Influence of rGO on the Crystallization Kinetics, Cytoxicity, and Electrical and Mechanical Properties of Poly (L-lactide-co-ε-caprolactone) Scaffolds

Biodegradable scaffolds of poly (L-lactide-co-ε-caprolactone) (PLCL) and reduced graphene oxide (rGO) were prepared by TIPS (thermally induced phase separation). The nonisothermal cold crystallization kinetics were investigated by differential scanning calorimetry (DSC) with various cooling rates. The experimental values indicate that nonisothermal crystallization improves with cooling rate, but the increasing rGO concentration delays crystallization at higher temperatures. The activation energies were calculated by the Kissinger equation; the values were very similar for PLCL and for its compounds with rGO. The electrical conductivity measurements show that the addition of rGO leads to a rapid transition from insulating to conductive scaffolds with a percolation value of ≈0.4 w/w. Mechanical compression tests show that the addition of rGO improves the mechanical properties of porous substrates. In addition, it is an anisotropic material, especially at compositions of 1% w/w of rGO. All of the samples with different rGO content up to 1% are cytotoxic for C2C12 myoblast cells.

Porous biomaterials for tissue engineering: a review

The field of biomaterials has grown rapidly over the past decades. Within this field, porous biomaterials have played a remarkable role in: (i) enabling the manufacture of complex three-dimensional structures; (ii) recreating mechanical properties close to those of the host tissues; (iii) facilitating interconnected structures for the transport of macromolecules and cells; and (iv) behaving as biocompatible inserts, tailored to either interact or not with the host body. This review outlines a brief history of the development of biomaterials, before discussing current materials proposed for use as porous biomaterials and exploring the state-of-the-art in their manufacture. The wide clinical applications of these materials are extensively discussed, drawing on specific examples of how the porous features of such biomaterials impact their behaviours, as well as the advantages and challenges faced, for each class of the materials.

Tissue-engineered repair material for pelvic floor dysfunction

Pelvic floor dysfunction (PFD) is a highly prevalent urogynecology disorder affecting many women worldwide, with symptoms including pelvic organ prolapse (POP), stress urinary incontinence (SUI), fecal incontinence, and overactive bladder syndrome (OAB). At present, the clinical treatments of PFD are still conservative and symptom-based, including non-surgical treatment and surgery. Surgical repair is an effective and durable treatment for PFD, and synthetic and biological materials can be used to enforce or reinforce the diseased tissue. However, synthetic materials such as polypropylene patches caused a series of complications such as mesh erosion, exposure, pain, and inflammation. The poor mechanical properties and high degradation speed of the biomaterial meshes resulted in poor anatomical reduction effect and limitation to clinical application. Therefore, the current treatment options are suboptimal. Recently, tissue-engineered repair material (TERM) has been applied to repair PFD and could markedly improve the prognosis of POP and SUI repair surgery in animal models. We review the directions and progression of TERM in POP and SUI repair. Adipose-derived stem cells (ADSCs) and endometrial mesenchymal stem cells (eMSCs) appear to be suitable cell types for scaffold seeding and clinical implantation. The multidisciplinary therapy approach to tissue engineering is a promising direction for tissue repair. More and longer follow-up studies are needed before determining cell types and materials for PFD repair.

Tissue engineering application combining epoxidized natural rubber blend and mesenchymal stem cells in in vivo response

This study aimed to investigate biocompatibility, integration, and tissue host response of the Poly (Lactic-co-Glycolic acid) (PLGA)/Poly (isoprene) (PI) epoxidized (PLGA/PIepox) innovative scaffold combined with adipose derived mesenchymal stem cells (ADSC). We implanted the scaffold subcutaneously on the back of 18 female rats and monitored them for up to 14 days. When compared to controls, PLGA/PIepox + ADSC demonstrated an earlier vascularization, a tendency of inflammation reduction, an adequate tissue integration, higher cell proliferation, and a tendency of expression of collagen decreasing. However, 14 days post-implantation we found similar levels of CD31, Ki67 and AE1/AE3 in PLGA/PIepox when compared to control groups. The interesting results, lead us to the assumption that PLGA/PIepox is able to provide an effective delivery system for ADSC on tissue host. This animal study assesses PLGA/PIepox + ADSC in in vivo tissue functionality and validation of use, serving as a proof of concept for future clinical translation as it presents an innovative and promising tissue engineering opportunity for the use in tissue reconstruction.

Scaffold strategies combined with mesenchymal stem cells in vaginal construction: a review

Tissue engineering has provided new treatment alternatives for tissue reconstruction. Advances in the tissue engineering field have resulted in mechanical support and biological substitutes to restore, maintain or improve tissue/organs structures and functions. The application of tissue engineering technology in the vaginal reconstruction treatment can not only provide mechanical requirements, but also offer tissue repairing as an alternative to traditional approaches. In this review, we discuss recent advances in cell-based therapy in combination with scaffolds strategies that can potentially be adopted for gynaecological transplantation.

Tissue Engineering Opportunities for Vaginal Replacement in a Pediatric Population

Treatment for children born with vaginal agenesis remains difficult, without a clear gold standard for tissue replacement. An autologous-engineered vaginal replacement would significantly improve quality of life for people born with this condition. The aim of this study was to critically review literature on the current state of tissue engineering for vaginal reconstruction in a pediatric population. An electronic literature search was conducted using PubMed for articles describing pediatric vaginal tissue engineering from January 2003 to December 2020. Nine studies met inclusion criteria and were reviewed. The model, methods, cell type and source, scaffold type, and time of analysis and evaluation were compared. Three studies used in vitro and six used an in vivo design. Of the six in vivo studies, one was able to investigate autologous vaginal epithelial cells in human clinical trials. This review discusses the current knowledge and progress of vaginal tissue engineered replacements that can potentially be used as a basis for both future preclinical animal and clinical human studies. Impact statement The current methods of treatment for congenital vaginal anomalies leave room for improvement. The state of tissue engineering may provide a method to improve the surgical interventions provided for these patients, in hopes of providing increased vaginal functionally and quality of life.

Preclinical biological and physicochemical evaluation of two-photon engineered 3D biomimetic copolymer scaffolds for bone healing

A major challenge in orthopedics is the repair of large non-union bone fractures. A promising therapy for this indication is the use of biodegradable bioinspired biomaterials that stabilize the fracture site, relieve pain and initiate bone formation and healing. This study uses a multidisciplinary evaluation strategy to assess immunogenicity, allergenicity, bone responses and physicochemical properties of a novel biomaterial scaffold. Two-photon stereolithography generated personalized custom-built scaffolds with a repeating 3D structure of Schwarz Primitive minimal surface unit cell with a specific pore size of ∼400 μm from three different methacrylated poly(d,l-lactide-co-ε-caprolactone) copolymers with lactide to caprolactone monomer ratios of 16 : 4, 18 : 2 and 9 : 1. Using in vitro and in vivo assays for bone responses, immunological reactions and degradation dynamics, we found that copolymer composition influenced the scaffold physicochemical and biological properties. The scaffolds with the fastest degradation rate correlated with adverse cellular effects and mechanical stiffness correlated with in vitro osteoblast mineralization. The physicochemical properties also correlated with in vivo bone healing and immune responses. Overall these observations provide compelling support for these scaffolds for bone repair and illustrate the effectiveness of a promising multidisciplinary strategy with great potential for the preclinical evaluation of biomaterials.

Emerging Nano/Micro-Structured Degradable Polymeric Meshes for Pelvic Floor Reconstruction

Pelvic organ prolapse (POP) is a hidden women's health disorder that impacts 1 in 4 women across all age groups. Surgical intervention has been the only treatment option, often involving non-degradable meshes, with variable results. However, recent reports have highlighted the adverse effects of meshes in the long term, which involve unacceptable rates of erosion, chronic infection and severe pain related to mesh shrinkage. Therefore, there is an urgent unmet need to fabricate of new class of biocompatible meshes for the treatment of POP. This review focuses on the causes for the downfall of commercial meshes, and discusses the use of emerging technologies such as electrospinning and 3D printing to design new meshes. Furthermore, we discuss the impact and advantage of nano-/microstructured alternative meshes over commercial meshes with respect to their tissue integration performance. Considering the key challenges of current meshes, we discuss the potential of cell-based tissue engineering strategies to augment the new class of meshes to improve biocompatibility and immunomodulation. Finally, this review highlights the future direction in designing the new class of mesh to overcome the hurdles of foreign body rejection faced by the traditional meshes, in order to have safe and effective treatment for women in the long term.

Tissue engineering approaches for treating pelvic organ prolapse using a novel source of stem/stromal cells and new materials

PURPOSE OF REVIEW

Nondegradable transvaginal polypropylene meshes for treating pelvic organ prolapse (POP) are now generally unavailable or banned. In this review, we summarize recent developments using tissue engineering approaches combining alternate degradable scaffolds with a novel source of mesenchymal stem/stromal cells from human endometrium (eMSC).

RECENT FINDINGS

Tissue engineering constructs comprising immunomodulatory, reparative eMSC and biomimetic materials with nanoarchitecture are a promising approach for vaginal repair and improving outcomes of POP surgery. Culture expansion of eMSC that maintains them (and other MSC) in the undifferentiated state has been achieved using a small molecule transforming growth factor-β receptor inhibitor, A83-01. The mechanism of action of A83-01 has been determined and its suitability for translation into the clinic explored. Novel blends of electrospun synthetic and natural polymers combined with eMSC shows this approach promotes host cell infiltration and slows biomaterial degradation that has potential to strengthen the vaginal wall during healing. Improving the preclinical ovine transvaginal surgical model by adapting the human clinical POP-Quantification system for selection of multiparous ewes with vaginal wall weakness enables assessment of this autologous eMSC/nanobiomaterial construct.

SUMMARY

A tissue engineering approach using autologous eMSC with degradable nanobiomaterials offers a new approach for treating women with POP.

3D printing of implantable elastic PLCL copolymer scaffolds

Poly(l-lactic acid) (PLLA) scaffolds have been used in regenerative medicine, however, they commonly suffer from low flexibility, restricting their application in the repair and reconstruction of soft tissues. In this study, poly(l-lactide-co-ε-caprolactone) (PLCL) copolymers were examined to modulate the elasticity of PLLA with the random presence of CL units in PLLA. Thermodynamic analysis revealed that the introduction of PCL could significantly decrease the melting point and glass transition temperature of PLLA, benefiting the extrusion and printing of PLCL. Diverse scaffolds with designed architectures including porous cubes with or without large holes, cambered plates with holes and round tubes could be easily constructed by 3D printing. In the process of elastic deformation, the maximum elastic stress of the copolymer scaffold was obviously increased from 19.6 to 31.5 MPa when the relative content of PCL was increased to 70%, while the elongation at break was evidently increased from 388% to about 1974%. The Young's modulus of PLCL was also significantly decreased (P < 0.05) in comparison with that of PLLA. PLCL scaffolds have good platelet and endotheliocyte adhesion ability and no obvious hemolysis was observed. In vivo subcutaneous implantation of PLCL scaffolds demonstrated superior biocompatibility. Collectively, this work highlights that copolymerization of PCL segments into PLLA is an effective approach to tune the 3D printability and the stiffness and elasticity of PLLA scaffolds. PLCL scaffolds hold great promise for the regeneration of soft tissues including but not limited to cartilage, myocardium, muscle, tendon and nervous tissues.