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To measure the force applied along the anterior and posterior vaginal walls in a cohort of 46 patients measured by a fiber-optic pressure sensor and determine if this correlates with vaginal parity and pelvic organ prolapse (POP).An intravaginal fiber-optic sensor measured pressure at nine locations along the anterior and posterior vaginal walls during a maximal voluntary pelvic floor muscle contraction (MVC). An automated probe dilation cycle measured the tissue resistance incorporating the vagina and surrounding anatomy. MVC and resting tissue resistance (RTR) were assessed between subjects grouped by the number of vaginal births and prolapse stage.A previous vaginal birth was associated with a significant threefold decrease in the overall anterior pressure measurement during MVC. Decreased anterior pressure measurements were observed at Sensors 1 and 3 (distal vagina) and, posteriorly at Sensors 4-6 (midvagina). Women with Stage 2 posterior prolapse exhibited a decreased MVC pressure in the midvagina than those with Stage 0/1. In this pilot study, there was no difference in the vaginal wall RTR according to previous vaginal birth or stage of prolapse.This pilot study found that a decrease in vaginal pressure measured during MVC is associated with vaginal birth and with posterior POP. Greater sample size is required to assess the role of resting tissue pressure measurement.

Mesenchymal stem cells (MSCs) that meet the International Society for Cellular Therapy (ISCT) criteria are obtained from placental tissue by plastic adherence. Historically, no known single marker was available for isolating placental MSCs (pMSCs) from the decidua basalis. As the decidua basalis is derived from the regenerative endometrium, we hypothesised that SUSD2, an endometrial perivascular MSC marker, would purify maternal perivascular pMSC. Perivascular pMSCs were isolated from the maternal placenta using SUSD2 magnetic bead sorting and assessed for the colony-forming unit-fibroblasts (CFU-F), surface markers, and in vitro differentiation into mesodermal lineages. Multi-colour immunofluorescence was used to colocalise SUSD2 and α-SMA, a perivascular marker in the decidua basalis. Placental stromal cell suspensions comprised 5.1%SUSD2+ cells. SUSD2 magnetic bead sorting of the placental stromal cells increased their purity approximately two-fold. SUSD2+ pMSCs displayed greater CFU-F activity than SUSD2- stromal fibroblasts (pSFs). However, both SUSD2+ pMSC and SUSD2- pSF underwent mesodermal differentiation in vitro, and both expressed the ISCT surface markers. Higher percentages of cultured SUSD2+ pMSCs expressed the perivascular markers CD146, CD140b, and SUSD2 than SUSD2- pSFs. These findings suggest that SUSD2 is a single marker that enriches maternal pMSCs, suggesting they may originate from eMSC. Placental decidua basalis can be used as an alternative source of MSC for clinical translation in situations where there is no access to endometrial tissue.

Cellular therapy is an emerging field in clinical and personalised medicine. Many adult mesenchymal stem/progenitor cells (MSC) or pluripotent derivatives are being assessed simultaneously in preclinical trials for their potential treatment applications in chronic and degenerative human diseases. Endometrial mesenchymal stem/progenitor cells (eMSC) have been identified as clonogenic cells that exist in unique perivascular niches within the uterine endometrium. Compared with MSC isolated from other tissue sources, such as bone marrow and adipose tissue, eMSC can be extracted through less invasive methods of tissue sampling, and they exhibit improvements in potency, proliferative capacity, and control of culture-induced differentiation. In this review, we summarize the potential cell therapy and tissue engineering applications of eMSC in pelvic organ prolapse (POP), emphasising their ability to exert angiogenic and strong immunomodulatory responses that improve tissue integration of novel surgical constructs for POP and promote vaginal tissue healing.

AIMS Pelvic floor disorders (PFDs) in women are a major public health concern. Current clinical methods for assessing PFDs are either subjective or confounded by interference from intra-abdominal pressure (IAP). This study introduces an intravaginal probe that can determine distributed vaginal pressure during voluntary exercises and measures the degree of vaginal tissue support independent of IAP fluctuations. METHODS An intravaginal probe was fabricated with 18 independent fiber-optic pressure transducers positioned along its upper and lower blades. Continuous pressure measurement along the anterior and posterior vaginal walls during the automated expansion of the probe enabled the resistance of the tissue to be evaluated as a function of displacement, in a manner reflecting the elastic modulus of the tissue. After validation in a simulated vaginal phantom, in vivo measurements were conducted in the relaxed state and during a series of voluntary exercises to gauge the utility of the device in women. RESULTS The probe reliably detected variations in the composition of sub-surface material in the vaginal phantom. During in-vivo measurements the probe detected distributed tissue elasticity in the absence of IAP change. In addition, the distribution of pressure along both anterior and posterior vaginal walls during cough, Valsalva and pelvic floor contraction was clearly resolved with a large variation observed between subjects. CONCLUSIONS Our data highlight the potential for the probe to assess the integrity of the vagina wall and support structures as an integrated functional unit. Further in vivo trials are needed to correlate data with clinical findings to assist in the assessment of PFDs.

Bacterial systems, especially using Escherichia coli, provide a useful system for recombinant production of collagen and collagen-like proteins. These systems provide high yields of products but have lacked the ability to introduce hydroxyproline when it is needed for stability and function. Recent progress, in the last 30 months, of animal-based recombinant proteins has focussed on further development of collagen peptide materials and their applications. The proposal of new approaches for incorporation of hydroxyproline may enhance the utility of these products and enable production of new materials. Bacterial, collagen-like constructs have also continued to be developed for use in understanding collagen structure and functions, while progress has also been made on their application as new biomedical materials.

Aloe vera (AV), a succulent plant belonging to the Liliaceae family, has been widely used for biomedical and pharmaceutical application. Its popularity stems from several of its bioactive components that have anti-oxidant, anti-microbial, anti-inflammatory and even immunomodulatory effects. Given such unique multi-modal biological impact, AV has been considered as a biomaterial for regenerative medicine and tissue engineering applications, where tissue repair and neo-angiogenesis are vital. This review outlines the growing scientific evidence that demonstrates the advantage of AV as tissue engineering scaffolds. We particularly highlight the recent advances in the application of AV-based scaffolds. From a tissue engineering perspective, it is pivotal that the implanted scaffolds strike an appropriate foreign body response to be well-accepted in the body without complications. Herein, we highlight the key cellular processes that regulate the foreign body response to implanted scaffolds and underline the immunomodulatory effects incurred by AV on the innate and adaptive system. Given that AV has several beneficial components, we discuss the importance of delving deeper into uncovering its action mechanism and thereby improving material design strategies for better tissue engineering constructs for biomedical applications.

Mesenchymal stem cells (MSCs) that meet the International Society for Cellular Therapy (ISCT) criteria are obtained from placental tissue by plastic adherence. Historically, no known single marker was available for isolating placental MSCs (pMSCs) from the decidua basalis. As the decidua basalis is derived from the regenerative endometrium, we hypothesised that SUSD2, an endometrial perivascular MSC marker, would purify maternal perivascular pMSC. Perivascular pMSCs were isolated from the maternal placenta using SUSD2 magnetic bead sorting and assessed for the colony-forming unit-fibroblasts (CFU-F), surface markers, and in vitro differentiation into mesodermal lineages. Multi-colour immunofluorescence was used to colocalise SUSD2 and α-SMA, a perivascular marker in the decidua basalis. Placental stromal cell suspensions comprised 5.1%SUSD2

Rare perivascular mesenchymal stromal cells (MSCs) with therapeutic properties have been identified in many tissues. Their rarity necessitates extensive in vitro expansion, resulting in spontaneous differentiation, cellular senescence and apoptosis, producing therapeutic products with variable quality and decreased potency. We previously demonstrated that A83-01, a transforming growth factor beta (TGF-&beta, ) receptor inhibitor, maintained clonogenicity and promoted the potency of culture-expanded premenopausal endometrial MSCs using functional assays and whole-transcriptome sequencing. Here, we compared the effects of A83-01 on MSCs derived from postmenopausal endometrium, menstrual blood, placenta decidua-basalis, bone marrow and adipose tissue. Sushi-domain-containing-2 (SUSD2+) and CD34+CD31&minus, CD45&minus, MSCs were isolated. Expanded MSCs were cultured with or without A83-01 for 7 days and assessed for MSC properties. SUSD2 identified perivascular cells in the placental decidua-basalis, and their maternal origin was validated. A83-01 promoted MSC proliferation from all sources except bone marrow and only increased SUSD2 expression and prevented apoptosis in MSCs from endometrial-derived tissues. A83-01 only improved the cloning efficiency of postmenopausal endometrial MSCs (eMSCs), and expanded adipose tissue MSCs (adMSCs) underwent significant senescence, which was mitigated by A83-01. MSCs derived from bone marrow (bmMSCs) were highly apoptotic, but A83-01 was without effect. A83-01 maintained the function and phenotype in MSCs cultured from endometrial, but not other, tissues. Our results also demonstrated that cellular SUSD2 expression directly correlates with the functional phenotype.

Human endometrial mesenchymal stem cells (eMSCs) are a well-characterized adult stem cell type with potential for use in regenerative medicine or cell therapy. As a proof of principle, we demonstrated that eMSCs promoted wound healing by reducing the inflammatory response through a paracrine action in a subcutaneous rat model of wound repair. However, an efficient protocol for culturing eMSCs in the undifferentiated state and a reliable method of labeling them for cell tracking were lacking. In this study, we investigated the use of a lentiviral vector containing the mCherry fluorescent reporter gene to transduce and label eMSCs following in vitro culturing in A83-01 containing medium, and different methods of tracing the labeled cells following transplantation under the kidney capsule of immunocompromised NSG mice. Perivascular SUSD2

Cellular therapy is an emerging field in clinical and personalised medicine. Many adult mesenchymal stem/progenitor cells (MSC) or pluripotent derivatives are being assessed simultaneously in preclinical trials for their potential treatment applications in chronic and degenerative human diseases. Endometrial mesenchymal stem/progenitor cells (eMSC) have been identified as clonogenic cells that exist in unique perivascular niches within the uterine endometrium. Compared with MSC isolated from other tissue sources, such as bone marrow and adipose tissue, eMSC can be extracted through less invasive methods of tissue sampling, and they exhibit improvements in potency, proliferative capacity, and control of culture-induced differentiation. In this review, we summarize the potential cell therapy and tissue engineering applications of eMSC in pelvic organ prolapse (POP), emphasising their ability to exert angiogenic and strong immunomodulatory responses that improve tissue integration of novel surgical constructs for POP and promote vaginal tissue healing.

Although the thymus is a primary lymphoid organ, its function is compromised by an age-induced loss of resident epithelial cells, which results in reduced naïve T cell output. This has important implications for immune recovery in aged and elderly patients following damage from cytoablative therapies. As thymic architecture plays a crucial role in naïve T cell development, a tissue specific scaffold that provides essential supporting matrix may assist in stem cell-based thymus regeneration to recreate complex organoids. Here we investigate thymus decellularization approaches that preserve major extracellular matrix components and support thymic epithelial cells for the generation of a functional thymic microenvironment with improved T cell output. We also established an in vitro, serum-free culture system that both maintains a progenitor thymic epithelial cell pool and drives their differentiation in the presence of decellularized thymic matrix. This approach enables further dissection of key cellular and niche components involved in thymic epithelial stem cell maintenance and T cell production.

If tolerated in biological environments, recombinant structural proteins offer the advantage that biological cues dictating cell attachment and material degradation can be modified as required for clinical application using genetic engineering. In this study, we investigate the biological response to materials generated from the recombinant honeybee silk protein, AmelF3, a structural protein that can be produced at high levels by fermentation in Escherichia coli. The protein can be readily purified from E. coli host cell proteins after transgenic production and fabricated into various material formats. When implanted subcutaneously according to International Standard ISO 10993 tests, materials generated from the purified recombinant protein were found to be noncytotoxic, inducing a transient weak immunogenic response and a chronic inflammatory response that resolved over time. While preliminary, this study supports the ongoing development of materials generated from this protein for biomedical applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1763-1770, 2019.

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

Endometrial mesenchymal stem/stromal cells (eMSCs) exhibit excellent regenerative capacity in the endometrial lining of the uterus following menstruation and high proliferative capacity in vitro. Bioprinting eMSCs onto a mesh could be a potential therapy for Pelvic Organ Prolapse (POP). This study reports a novel strategy targeting vaginal repair using bioprinting of eMSCs encapsulated in a hydrogel and3D melt electrospun mesh to generate a tissue engineering construct. Following a CAD, 3D printed poly e-caprolactone (PCL) meshes were fabricated using melt electrospinning (MES) at different temperatures using a GMP clinical grade GESIM Bioscaffolder. Electron and atomic force microscopies revealed that MES meshes fabricated at 100°C and with a speed 20 mm/sec had the largest open pore diameter (47.2 ± 11.4 μm) and the lowest strand thickness (121.4 ± 46 μm) that promoted optimal eMSC attachment. An Aloe Vera-Sodium Alginate (AV-ALG) composite based hydrogel was optimised to a 1:1 mixture (1%AV-1%ALG) and eMSCs, purified from human endometrial biopsies, were then bioprinted in this hydrogel onto the MES printed meshes. Acute in vivo foreign body response assessment in NSG mice revealed that eMSC printed on MES constructs promoted tissue integration, eMSC retention and an anti-inflammatory M2 macrophage phenotype characterised by F4/80+CD206+ colocalization. Our results address an unmet medical need highlighting the potential of alternative 3D bioprinted eMSC-MES meshes as a novel approach to overcome the current challenges with non-degradable knitted meshes in POP treatment.

Vaginal childbirth causes significant maternal tissue injury which can later leads to incurable disorders such as pelvic organ prolapse (POP). This study introduces an immediate vaginal tissue treatment using Aloe Vera (AV)-Alginate (ALG) hydrogel (Hyd) for delivering maternal endometrium derived Mesenchymal stem cells (eMSCs) to promote early healing in a rat simulated birth injury (SBI) model. Vaginal trauma after SBI was evidenced by increased vaginal diameter and inflammatory response. A lack of therapy showed significant reduction of smooth muscle content, increased elastin and increased tissue stiffness, indicative of fibrotic healing. Local injection with hydrogel (Hyd T) or with eMSC in hydrogel (Hyd/eMSC T) had significant impact on birth injury reversal. Hyd/eMSC T significantly improvement smooth muscle and elastin content, comparable to uninjured control vagina. At the nanoscopic level, injury caused disorganisation of structural collagen with increased D period but intervention with Hyd/eMSC T, normalised collagen structure and significantly reduced tissue stiffness. Hyd/eMSC injection showed significant immunomodulation evidenced by lowered M1:M2 ratio while restoring connective tissue composition after 6-weeks. Immediate treatment of severe vaginal birth trauma with therapeutic eMSCs delivered in AV-ALG hydrogel may be a potential new treatment strategy for healing birth injury and preventing future POP in women.

Recombinant bacterial collagens provide a new opportunity for safe biomedical materials. They are readily expressed in Escherichia coli in good yield and can be readily purified by simple approaches. However, recombinant proteins are limited in that direct secondary modification during expression is generally not easily achieved. Thus, inclusion of unusual amino acids, cyclic peptides, sugars, lipids, and other complex functions generally needs to be achieved chemically after synthesis and extraction. In the present study, we have illustrated that bacterial collagens that have had their sequences modified to include cysteine residue(s), which are not normally present in bacterial collagen-like sequences, enable a range of specific chemical modification reactions to be produced. Various model reactions were shown to be effective for modifying the collagens. The ability to include alkyne (or azide) functions allows the extensive range of substitutions that are available via "click" chemistry to be accessed. When bifunctional reagents were used, some crosslinking occurred to give higher molecular weight polymeric proteins, but gels were not formed. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 806-813, 2017.

Summary Human endometrium is a highly regenerative tissue, undergoing more than 400 cycles of proliferation, differentiation, and shedding during a woman' reproductive life. Adult stem cells, including mesenchymal stem/stromal cells (MSCs), are likely responsible for the immense cellular turnover in human endometrium. The unique properties of MSCs, including high proliferative ability, self-renewal, differentiation to mesodermal lineages, secretion of angiogenic factors, and many other growth-promoting factors make them useful candidates for cellular therapy and tissue engineering. In this review, we summarize the identification and characterization of newly discovered MSCs from the human endometrium: their properties, the surface markers used for their prospective isolation, their perivascular location in the endometrium, and their potential application in cellular therapies. Significance The endometrium, or the lining of uterus, has recently been identified as a new and accessible source of mesenchymal stem cells, which can be obtained without anesthesia. Endometrial mesenchymal stem cells have comparable properties to bone marrow and adipose tissue mesenchymal stem cells. Endometrial mesenchymal stem cells are purified with known and novel perivascular surface markers and are currently under investigation for their potential use in cellular therapy for several clinical conditions with significant burden of disease.

A range of non-animal collagens has been described, derived from bacterial species, which form stable triple-helical structures without the need for secondary modification to include hydroxyproline in the sequence. The non-animal collagens studied to date are typically smaller than animal interstitial collagens, around one quarter the length and do not pack into large fibrillar aggregates like those that are formed by the major animal interstitial collagens. A consequence of this for biomedical products is that fabricated items, such as collagen sponges, are not as mechanically and dimensionally stable as those of animal collagens. In the present study, we examined the production of larger, polymeric forms of non-animal collagens through introduction of tyrosine and cysteine residues that can form selective crosslinks through oxidation. These modifications allow the formation of larger aggregates of the non-animal collagens. When Tyr residues were incorporated, gels were obtained. And with Cys soluble aggregates were formed. These materials can be formed into sponges that are more stable than those formed without these modifications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2369-2376, 2016.

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.

The current urogynecological clinical meshes trigger unfavorable foreign body response which leads to graft failure in the long term. To overcome the present challenge, we applied a tissue engineering strategy using endometrial SUSD2+ mesenchymal stem cells (eMSCs) with high regenerative properties. This study delves deeper into foreign body response to SUSD2+ eMSC based degradable PLACL/gelatin nanofiber meshes using a mouse model targeted at understanding immunomodulation and mesh integration in the long term. Delivery of cells with nanofiber mesh provides a unique topography that enables entrapment of therapeutic cells for up to 6 weeks that promotes substantial cellular infiltration of host anti-inflammatory macrophages. As a result, degradation rate and tissue integration are highly impacted by eMSCs, revealing an unexpected level of implant integration over 6 weeks in vivo. From a clinical perspective, such immunomodulation may aid in overcoming the current challenges and provide an alternative to an unmet women's urogynecological health need.

The immunomodulatory properties of human endometrial mesenchymal stem cells (eMSC) have not been well characterised. Initial studies showed that eMSC modulated the chronic inflammatory response to a non-degradable polyamide/gelatin mesh in a xenogeneic rat skin wound repair model, but the mechanism remains unclear. In this study, we investigated the immunomodulatory effect of eMSC on the macrophage response to polyamide/gelatin composite mesh in an abdominal subcutaneous wound repair model in C57BL6 immunocompetent and NSG (NOD-Scid-IL2Rgamma null ) immunocompromised mice to determine whether responses differed in the absence of an adaptive immune system and NK cells. mCherry lentivirus-labelled eMSC persisted longer in NSG mice, inducing longer term paracrine effects. Inclusion of eMSC in the mesh reduced inflammatory cytokine (Il-1β, Tnfα) secretion, and in C57BL6 mice reduced CCR7+ M1 macrophages surrounding the mesh on day 3 and increased M2 macrophage marker mRNA (Arg1, Mrc1, Il10) expression at days 3 and 7. In NSG mice, these effects were delayed and only observed at days 7 and 30 in comparison with controls implanted with mesh alone. These results show that the differences in the immune status in the two animals directly affect the survival of xenogeneic eMSC which leads to differences in the short-term and long-term macrophage responses to implanted meshes.

Regenerative medicine strategies for restoring articular cartilage face significant challenges to recreate the complex and dynamic biochemical and biomechanical functions of native tissues. As an approach to recapitulate the complexity of the extracellular matrix, collagen-mimetic proteins offer a modular template to incorporate bioactive and biodegradable moieties into a single construct. We modified a Streptococcal collagen-like 2 protein with hyaluronic acid (HA) or chondroitin sulfate (CS)-binding peptides and then cross-linked with a matrix metalloproteinase 7 (MMP7)-sensitive peptide to form biodegradable hydrogels. Human mesenchymal stem cells (hMSCs) encapsulated in these hydrogels exhibited improved viability and significantly enhanced chondrogenic differentiation compared to controls that were not functionalized with glycosaminoglycan-binding peptides. Hydrogels functionalized with CS-binding peptides also led to significantly higher MMP7 gene expression and activity while the HA-binding peptides significantly increased chondrogenic differentiation of the hMSCs. Our results highlight the potential of this novel biomaterial to modulate cell-mediated processes and create functional tissue engineered constructs for regenerative medicine applications.

Current regulatory requirements demand an in-depth understanding and validation of protocols used in tissue banking. The aim of this work was to characterize the quality of split thickness skin allografts cryopreserved or manufactured using highly concentrated solutions of glycerol (50, 85 or 98%), where tissue water activity (aw), histology and birefringence changes were chosen as parameters. Consistent aw outcomes validated the proposed processing protocols. While no significant changes in tissue quality were observed under bright-field microscopy or in collagen birefringence, in-process findings can be harnessed to fine-tune and optimize manufacturing outcomes in particular when further radiation sterilization is considered. Furthermore, exposing the tissues to 85% glycerol seems to derive the most efficient outcomes as far as aw and control of microbiological growth.

Pelvic Organ Prolapse (POP) is a major clinical burden affecting 25% of women, with vaginal delivery a major contributing factor. We hypothesised that increasing parity weakens the vagina by altering the extracellular matrix proteins and smooth muscle thereby leading to POP vulnerability. We used a modified POP-quantification (POP-Q) system and a novel pressure sensor to measure vaginal wall weakness in nulliparous, primiparous and multiparous ewes. These measurements were correlated with histological, biochemical and biomechanical properties of the ovine vagina. Primiparous and multiparous ewes had greater displacement of vaginal tissue compared to nulliparous at points Aa, Ap and Ba and lower pressure sensor measurements at points equivalent to Ap and Ba. Vaginal wall muscularis of multiparous ewes was thinner than nulliparous and had greater elastic fibre content. Collagen content was lower in primiparous than nulliparous ewes, but collagen organisation did not differ. Biomechanically, multiparous vaginal tissue was weaker and less stiff than nulliparous. Parity had a significant impact on the structure and function of the ovine vaginal wall, as the multiparous vaginal wall was weaker and had a thinner muscularis than nulliparous ewes. This correlated with “POP-Q” and pressure sensor measurements showing greater tissue laxity in multiparous compared to nulliparous ewes.

Pelvic organ prolapse is a major hidden burden affecting almost one in four women. It is treated by reconstructive surgery, often augmented with synthetic mesh. To overcome the growing concerns of using current synthetic meshes coupled with the high risk of reoperation, a tissue engineering strategy has been developed, adopting a novel source of mesenchymal stem cells. These cells are derived from the highly regenerative endometrial lining of the uterus (eMSCs) and will be delivered in vivo using a new gelatin-coated polyamide scaffold. In this study, gelatin properties were optimized by altering the gelatin concentration and extent of crosslinking to produce the desired gelation and degradation rate in culture. Following cell seeding of uncoated polyamide (PA) and gelatin-coated meshes (PA+G), the growth rate of eMSCs on the PA+G scaffolds was more than that on the PA alone, without compromising cell shape. eMSCs cultured on the PA+G scaffold retained their phenotype, as demonstrated by W5C5/SUSD2 (eMSC-specific marker) immunocytochemistry. Additionally, eMSCs were induced to differentiate into smooth muscle cells (SMC), as shown by immunofluorescence for smooth muscle protein 22 and smooth muscle myosin heavy chain. eMSCs also differentiated into fibroblast-like cells when treated with connective tissue growth factor with enhanced detection of Tenascin-C and collagen type I as well as new tissue formation, as seen by Masson's trichrome. In summary, it was demonstrated that the PA+G scaffold is an appropriate platform for eMSC delivery, proliferation and differentiation into SMC and fibroblasts, with good biocompatibility and the capacity to regenerate neo-tissue.

The present study has evaluated a commercial pericardial material for its capacity to assist as a natural extracellular matrix (ECM) patch for the delivery and retention of mesenchymal stem cells for cardiac repair. The repair of cardiac tissue with cells delivered by an appropriate bioscaffold is expected to offer a superior, long-lasting treatment strategy. The present material, CardioCel®, is based on acellular pericardium that has been stabilized by treatments, including a low concentration of glutaraldehyde, that eliminate calcification after implantation. In the present study, we have assessed this material using human bone marrow mesenchymal stem cells at various cell densities under standard, static cell culture conditions. The initial seeding densities were monitored to evaluate the extent of cell attachment and cell viability, with subsequent cell proliferation assessed up to 4 weeks using an MTS assay. Cell morphology, infiltration, and spreading were tracked using scanning electron microscopy and phalloidin staining. The efficacy of long-term cell survival was further assessed by examining the extent and type of new tissue formation on seeded scaffolds at 70 days; both type I and type III collagens were present in fibrillar structures on these scaffolds indicating that the seeded stem cells had the capacity to differentiate into collagen-producing cells necessary to repair damaged ECM. These data show that the CardioCel® scaffold is an appropriate substrate for the stem cells and has the potential to both retain seeded stem cells and to act as a template for cell propagation and new tissue formation.

Cuvierian tubules are expelled as a defence mechanism against predators by various species within the family Holothuridae. When the tubules are expelled, they become sticky almost immediately and ensnare the predator. The mechanism of this rapid adhesion is not clear, but proteins on the surface of the expelled tubules are widely believed to be involved. This study has examined such proteins from Holothuria dofleinii, sourced from adhesive prints left on glass after the removal of adhered tubules. Gel electrophoresis showed that seven strongly staining protein bands were consistently present in all samples, with molecular masses ranging from 89 to 17 kDa. N-terminal sequence data was obtained from two bands, while others seemed blocked. Tandem mass spectrometry-based sequencing of tryptic peptides derived from individual protein bands indicated that the proteins were unlikely to be homopolymers. PCR primers designed using the peptide sequences enabled us to amplify, clone and sequence cDNA segments relating to four gel bands; for each, the predicted translation product contained other peptide sequences observed for that band that had not been used in primer design. Database searches using the peptide and cDNA-encoded sequences suggest that two of the seven proteins are novel and one is a C-type lectin, while-surprisingly-at least three of the other four are closely related to enzymes associated with the pentose phosphate cycle and glycolysis. We discuss precedents in which lectins and metabolic enzymes are involved in attachment and adhesion phenomena.

Although rhBMP-2 has excellent ability to accelerate the repair of normal bone defects, limitations of its application exist in the high cost and potential side effects. This study aimed to develop a composite photopolymerisable hydrogel incorporating rhBMP-2 loaded 2-N, 6-O-sulfated chitosan nanoparticles (PH/rhBMP-2/NPs) as the bone substitute to realize segmental bone defect repair at a low growth factor dose. Firstly rhBMP-2 loaded 2-N, 6-O-sulfated chitosan nanoparticles (rhBMP-2/NPs) were prepared and characterized by DLS and TEM. Composite materials, PH/rhBMP-2/NPs were developed and investigated by SEM-EDS as well as a series of physical characterizations. Using hMSCs as an in vitro cell model, composite photopolymerisable hydrogels incorporating NPs (PH/NPs) showed good cell viability, cell adhesion and time dependent cell ingrowth. In vitro release kinetics of rhBMP-2 showed a significantly lower initial burst release from the composite system compared with the growth factor-loaded particles alone or encapsulated directly within the hydrogel, followed by a slow release over time. The bioactivity of released rhBMP-2 was validated by alkaline phosphatase (ALP) activity as well as a mineralization assay. In in vivo studies, the PH/rhBMP-2/NPs induced ectopic bone formation in the mouse thigh. In addition, we further investigated the in vivo effects of rhBMP-2-loaded scaffolds in a rabbit radius critical defect by three dimensional micro-computed tomographic (μCT) imaging, histological analysis, and biomechanical measurements. Animals implanted with the composite hydrogel containing rhBMP-2-loaded nanoparticles underwent gradual resorption with more pronounced replacement by new bone and induced reunion of the bone marrow cavity at 12 weeks, compared with animals implanted with hydrogel encapsulated growth factors alone. These data provided strong evidence that the composite PH/rhBMP-2/NPs are a promising substitute for bone tissue engineering.

The widespread use of synthetic transvaginal polypropylene mesh for treating Pelvic Organ Prolapse (POP) has been curtailed due to serious adverse effects highlighted in 2008 and 2011 FDA warnings and subsequent legal action. We are developing new synthetic mesh to deliver endometrial mesenchymal stem cells (eMSC) to improve mesh biocompatibility and restore strength to prolapsed vaginal tissue. Here we evaluated knitted polyamide (PA) mesh in an ovine multiparous model using transvaginal implantation and matched for the degree of POP. Polyamide mesh dip-coated in gelatin and stabilised with 0.5% glutaraldehyde (PA/G) were used either alone or seeded with autologous ovine eMSC (eMSC/PA/G), which resulted in substantial mesh folding, poor tissue integration and 42% mesh exposure in the ovine model. In contrast, a two-step insertion protocol, whereby the uncoated PA mesh was inserted transvaginally followed by application of autologous eMSC in a gelatin hydrogel onto the mesh and crosslinked with blue light (PA + eMSC/G), integrated well with little folding and no mesh exposure. The autologous ovine eMSC survived 30 days in vivo but had no effect on mesh integration. The stiff PA/G constructs provoked greater myofibroblast and inflammatory responses in the vaginal wall, disrupted the muscularis layer and reduced elastin fibres compared to PA + eMSC/G constructs. This study identified the superiority of a two-step protocol for implanting synthetic mesh in cellular compatible composite constructs and simpler surgical application, providing additional translational value.

An excessive foreign body response (FBR) has contributed to the adverse events associated with polypropylene mesh usage for augmenting pelvic organ prolapse surgery. Consequently, current biomaterial research considers the critical role of the FBR and now focuses on developing better biocompatible biomaterials rather than using inert implants to improve the clinical outcomes of their use. Tissue engineering approaches using mesenchymal stem cells (MSCs) have improved outcomes over traditional implants in other biological systems through their interaction with macrophages, the main cellular player in the FBR. The unique angiogenic, immunomodulatory and regenerative properties of MSCs have a direct impact on the FBR following biomaterial implantation. In this review, we focus on key aspects of the FBR to tissue-engineered MSC-based implants for supporting pelvic organs and beyond. We also discuss the immunomodulatory effects of the recently discovered endometrial MSCs on the macrophage response to new biomaterials designed for use in pelvic floor reconstructive surgery. We conclude with a focus on considerations in biomaterial design that take into account the FBR and will likely influence the development of the next generation of biomaterials for gynaecological applications.

The deposition of new collagen in association with a medical implant has been studied using expanded polytetrafluoroethylene vascular replacement samples implanted subcutaneously in sheep, for up to 28 days. New type I collagen mRNA synthesis was followed by in situ hybridization, while the accumulation of new collagen types III, V, VI, XII, and XIV was followed by immunohistochemistry. All the collagen detected in the pores of the implant were newly deposited at various times after implantation and were not due to any pre-existing dermal collagen that may have been present around the implant. Collagen deposition was seen initially surrounding the implant and, with time, was seen to infiltrate within its pores. In situ hybridization showed that the majority of infiltrating cells had switched on mRNA that coded for type I collagen production. Histology showed that cellular infiltration increased with time, accompanied by increasing collagen deposition. The deposition of different collagen types happened at different rates. The type V and VI collagens preceded the major interstitial collagens in the newly deposited tissue, although at longer time points, detection of type V collagen appeared to decrease. After disruption of the interstitial collagens with enzyme, the "masked" type V collagen was clearly still visible by immunohistochemistry. Little type XII collagen could be seen within the porous mesh, although it was seen in the surrounding tissues. By contrast, type XIV was seen throughout the porous structure of the implanted mesh, with less being visible outside the material where type XII was more abundant.

Bacterially derived triple-helical, collagen-like proteins are attractive as potential biomedical materials. The collagen-like domain of the Scl2 protein from S. pyogenes lacks any specific binding sites for mammalian cells yet possesses the inherent structural integrity of the collagen triple-helix of animal collagens. It can, therefore, be considered as a structurally-stable "blank slate" into which various defined, biological sequences, derived from animal collagens, can be added by substitutions or insertions, to enable production of novel designed materials to fit specific functional requirements. In the present study, we have used site directed mutagenesis to substitute two functional sequences, one for heparin binding and the other for integrin binding, into different locations in the triple-helical structure. This provided three new constructs, two containing the single substitutions and one containing both substitutions. The stability of these constructs was marginally reduced when compared to the unmodified sequence. When compared to the unmodified bacterial collagen, both the modified collagens that contain the heparin binding site showed marked binding of fluorescently labeled heparin. Similarly, the modified collagens from both constructs containing the integrin binding site showed significant adhesion of L929 cells that are known to possess the appropriate integrin receptor. C2C12 cells that lack any appropriate integrins did not bind. These data show that bacterial collagen-like sequences can be modified to act like natural extracellular matrix collagens by inserting one or more unique biological domains with defined function.

We have previously identified and purified multipotent mesenchymal stromal cell (MSC)-like cells in the highly regenerative endometrial lining of the human uterus (eMSC) as CD140b+CD146+ cells. Due to ease of accessibility with minimal morbidity via biopsy, we are proposing to use eMSC in cell-based therapies; however, culture conditions compliant with Good Manufacturing Practice have not been established for eMSC. The aim of this study was to optimize serum-free and xeno-free culture conditions for expansion of eMSC for potential clinical use. Real-time cell assessment (Xcelligence) and MTS viability assays were used to measure attachment and proliferation of freshly isolated, flow cytometry-sorted CD140b+CD146+ eMSC cultured in several commercially available and in-house serum-free and xeno-free media in combination with five attachment matrices (fibronectin, collagen, gelatin, laminin, and Cell Start-XF®). Comparisons were made with a standard serum-containing medium, DMEM/F-12/10% fetal bovine serum. Under all conditions examined, eMSC attachment and proliferation was greatest using a fibronectin matrix, with Lonza TP-SF® and our in-house DMEM/SF/FGF2/EGF serum-free xeno-product-containing medium similar to serum-containing medium. Hypoxia increased eMSC proliferation in the DMEM/SF/FGF2/EGF serum-free medium. Culture of eMSC for 7 days on a fibronectin matrix in DMEM/SF/FGF2/EGF serum-free media in 5% O2 maintained greater numbers of undifferentiated eMSC expressing CD140b, CD146, and W5C5 compared to culture under similar conditions in Lonza TP-SF medium. However, the percentage of cells expressing typical MSC phenotypic markers, CD29, CD44, CD73, and CD105, were similar for both media. EMSC showed greater expansion in 2D compared to 3D culture on fibronectin-coated microbeads using the optimized DMEM/SF/FGF2/EGF medium in 5% O2. In the optimized 2D culture conditions, eMSC retained CFU activity, multipotency, and MSC surface phenotype, representing the first steps in their preparation for potential clinical use.

Graphical abstract, Recapitulation of the articular cartilage microenvironment for regenerative medicine applications faces significant challenges due to the complex and dynamic biochemical and biomechanical nature of native tissue. Towards the goal of biomaterial designs that enable the temporal presentation of bioactive sequences, recombinant bacterial collagens such as Streptococcal collagen-like 2 (Scl2) proteins can be employed to incorporate multiple specific bioactive and biodegradable peptide motifs into a single construct. Here, we first modified the backbone of Scl2 with glycosaminoglycan-binding peptides and cross-linked the modified Scl2 into hydrogels via matrix metalloproteinase 7 (MMP7)-cleavable or non-cleavable scrambled peptides. The cross-linkers were further functionalized with a tethered RGDS peptide creating a system whereby the release from an MMP7-cleavable hydrogel could be compared to a system where release is not possible. The release of the RGDS peptide from the degradable hydrogels led to significantly enhanced expression of collagen type II (3.9-fold increase), aggrecan (7.6-fold increase), and SOX9 (5.2-fold increase) by human mesenchymal stem cells (hMSCs) undergoing chondrogenesis, as well as greater extracellular matrix accumulation compared to non-degradable hydrogels (collagen type II; 3.2-fold increase, aggrecan; 4-fold increase, SOX9; 2.8-fold increase). Hydrogels containing a low concentration of the RGDS peptide displayed significantly decreased collagen type I and X gene expression profiles, suggesting a major advantage over either hydrogels functionalized with a higher RGDS peptide concentration, or non-degradable hydrogels, in promoting an articular cartilage phenotype. These highly versatile Scl2 hydrogels can be further manipulated to improve specific elements of the chondrogenic response by hMSCs, through the introduction of additional bioactive and/or biodegradable motifs. As such, these hydrogels have the possibility to be used for other applications in tissue engineering. Statement of Significance Recapitulating aspects of the native tissue biochemical microenvironment faces significant challenges in regenerative medicine and tissue engineering due to the complex and dynamic nature of the tissue. The ability to take advantage of, mimic, and modulate cell-mediated processes within novel naturally-derived hydrogels is of great interest in the field of biomaterials to generate constructs that more closely resemble the biochemical microenvironment and functions of native biological tissues such as articular cartilage. Towards this goal, the temporal presentation of bioactive sequences such as RGDS on the chondrogenic differentiation of human mesenchymal stem cells is considered important as it has been shown to influence the chondrogenic phenotype. Here, a novel and versatile platform to recreate a high degree of biological complexity is proposed, which could also be applicable to other tissue engineering and regenerative medicine applications.

The aim of this study was to develop a 2-N, 6-O-sulfated chitosan (26SCS) modified electrospun fibrous PCL scaffold for bone morphogenetic protein-2 (BMP-2) delivery to improve osteoinduction. The PCL scaffold was modified by an aminolysis reaction using ethylenediamine (ED) and 26SCS was immobilized via electrostatic interactions (PCL-N-S). Scaffolds were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. In vitro BMP-2 adsorption and release kinetics indicated that modified PCL-N-S scaffolds showed higher levels of binding of BMP-2 (about 30-100 times), moderative burst release (about one third), and prolonged releasing time compared to the unmodified PCL scaffold. The bioactivity of released BMP-2 determined by alkaline phosphatase (ALP) activity assay was maintained and improved 8-12 times with increasing concentration of immobilized 26SCS on the scaffolds. In vitro studies demonstrated that bone marrow mesenchymal stem cells (BMSCs) attached more readily to the PCL-N-S scaffolds with increased spreading. In conclusion, 26SCS modified PCL scaffolds can be a potent system for the sustained and bioactive delivery of BMP-2.

Pelvic organ prolapse (POP) occurs when changes to the pelvic organ support structures cause descent or herniation of the pelvic organs into the vagina. Clinical evaluation of POP is a series of manual measurements known as the pelvic organ prolapse quantification (POP-Q) score. However, it fails to identify the mechanism causing POP and relies on the skills of the practitioner. We report on a modified vaginal speculum incorporating a double-helix fiber-Bragg grating structure for distributed pressure measurements along the length of the vagina and include preliminary data in an ovine model of prolapse. Vaginal pressure profiles were recorded at 10 Hz as the speculum was dilated incrementally up to 20 mm. At 10-mm dilation, nulliparous sheep showed higher mean pressures ( 102 ± 46 ?? mmHg ) than parous sheep ( 39 ± 23 ?? mmHg ) ( P = 0.02 ), attributable largely to the proximal (cervical) end of the vagina. In addition to overall pressure variations, we observed a difference in the distribution of pressure that related to POP-Q measurements adapted for the ovine anatomy, showing increased tissue laxity in the upper anterior vagina for parous ewes. We demonstrate the utility of the fiber-optic instrumented speculum for rapid distributed measurement of vaginal support.

Recombinant bacterial collagens provide a new opportunity for safe biomedical materials. They are readily expressed in Escherichia coli in good yield and can be readily purified by simple approaches. However, recombinant proteins are limited in that direct secondary modification during expression is generally not easily achieved. Thus, inclusion of unusual amino acids, cyclic peptides, sugars, lipids, and other complex functions generally needs to be achieved chemically after synthesis and extraction. In the present study, we have illustrated that bacterial collagens that have had their sequences modified to include cysteine residue(s), which are not normally present in bacterial collagen-like sequences, enable a range of specific chemical modification reactions to be produced. Various model reactions were shown to be effective for modifying the collagens. The ability to include alkyne (or azide) functions allows the extensive range of substitutions that are available via "click" chemistry to be accessed. When bifunctional reagents were used, some crosslinking occurred to give higher molecular weight polymeric proteins, but gels were not formed. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 806-813, 2017.

Pelvic Organ Prolapse (POP) is the herniation of pelvic organs into the vagina. Despite broad acceptance of mesh use in POP surgical repair, the complication rate is unacceptable. We hypothesized that collagen-containing polypropylene (PP) mesh types could modulate mesh-tissue integration and reduce long-term inflammation, thereby reducing mesh-associated complications. This study compared the long-term tissue response to an unmodified PP mesh and two collagen containing meshes in an ovine model which has similar pelvic anatomy and vaginal size to human. Three commercially available macroporous PP meshes, uncoated PP mesh (Avaulta Solo) (PP), the same textile PP mesh layered with a sheet of cross-linked porcine acellular matrix (Avaulta Plus) (PP-ACM) and a different yet also macroporous PP (Sofradim) mesh coated with solubilized atelocollagen (Ugytex) (PP-sCOL) were implanted in the ovine vagina and tissue explanted after 60 and 180days. The macrophage phenotype and response to implanted meshes, and vascularity were quantified by immunostaining and morphometry. We quantified changes in extracellular matrix composition biochemically and collagen organisation and percentage area around the interface of the mesh implants by Sirius Red birefringence and morphometry. PP-ACM induced a more sustained inflammatory response, indicated by similar CD45(+) leukocytes but reduced CD163(+) M2 macrophages at 60days (P0.05). PP-sCOL increased Von Willebrand Factor (vWF)-immunoreactive vessel profiles after 60days. At the micro-molecular level, collagen birefringence quantification revealed significantly fewer mature collagen fibrils (red, thick fibrils) at the mesh-tissue interface than control tissue for all mesh types (P0.001) but still significantly greater than the proportion of immature (green thin fibrils) at 60days (P0.05). The proportion of mature collagen fibrils increased with time around the mesh filaments, particularly those containing collagen. The total collagen percent area at the mesh interface was greatest around the PP-ACM mesh at 60days (P0.05). By 180days the total mature and immature collagen fibres at the interface of the mesh filaments resembled that of native tissue. In particular, these results suggest that both meshes containing collagen evoke different types of tissue responses at different times during the healing response yet both ultimately lead to physiological tissue formation approaching that of normal tissue.Pelvic organ prolapse (POP) is the descent of the pelvic organs to the vagina. POP affects more than 25% of all women and the lifetime risk of undergoing POP surgery is 19%. Although synthetic polypropylene (PP) meshes have improved the outcome of the surgical treatment for POP, there was an unacceptable rate of adverse events including mesh exposure and contracture. It is hypothesized that coating the PP meshes with collagen would provide a protective effect by preventing severe mesh adhesions to the wound, resulting in a better controlled initial inflammatory response, and diminished risk of exposure. In this study we assessed the effect of two collagen-containing PP meshes on the long-term vaginal tissue response using new techniques to quantify these tissue responses.

A range of non-animal collagens has been described, derived from bacterial species, which form stable triple-helical structures without the need for secondary modification to include hydroxyproline in the sequence. The non-animal collagens studied to date are typically smaller than animal interstitial collagens, around one quarter the length and do not pack into large fibrillar aggregates like those that are formed by the major animal interstitial collagens. A consequence of this for biomedical products is that fabricated items, such as collagen sponges, are not as mechanically and dimensionally stable as those of animal collagens. In the present study, we examined the production of larger, polymeric forms of non-animal collagens through introduction of tyrosine and cysteine residues that can form selective crosslinks through oxidation. These modifications allow the formation of larger aggregates of the non-animal collagens. When Tyr residues were incorporated, gels were obtained. And with Cys soluble aggregates were formed. These materials can be formed into sponges that are more stable than those formed without these modifications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2369-2376, 2016.

Tissue engineering strategies for repairing and regenerating articular cartilage face critical challenges to recapitulate the dynamic and complex biochemical microenvironment of native tissues. One approach to mimic the biochemical complexity of articular cartilage is through the use of recombinant bacterial collagens as they provide a well–defined biological ‘blank template’ that can be modified to incorporate bioactive and biodegradable peptide sequences within a precisely defined three–dimensional system. We customized the backbone of a Streptococcal collagen–like 2 (Scl2) protein with heparin–binding, integrin–binding, and hyaluronic acid–binding peptide sequences previously shown to modulate chondrogenesis and then cross–linked the recombinant Scl2 protein with a combination of matrix metalloproteinase 7 (MMP7)– and aggrecanase (ADAMTS4)–cleavable peptides at varying ratios to form biodegradable hydrogels with degradation characteristics matching the temporal expression pattern of these enzymes in human mesenchymal stem cells (hMSCs) during chondrogenesis. hMSCs encapsulated within the hydrogels cross–linked with both degradable peptides exhibited enhanced chondrogenic characteristics as demonstrated by gene expression and extracellular matrix deposition compared to the hydrogels cross–linked with a single peptide. Additionally, these combined peptide hydrogels displayed increased MMP7 and ADAMTS4 activities and yet increased compression moduli after 6 weeks, suggesting a positive correlation between the degradation of the hydrogels and the accumulation of matrix by hMSCs undergoing chondrogenesis. Our results suggest that including dual degradation motifs designed to respond to enzymatic activity of hMSCs going through chondrogenic differentiation led to improvements in chondrogenesis. Our hydrogel system demonstrates a bimodal enzymatically degradable biological platform that can mimic native cellular processes in a temporal manner. As such, this novel collagen–mimetic protein, cross–linked via multiple enzymatically degradable peptides, provides a highly adaptable and well defined platform to recapitulate a high degree of biological complexity, which could be applicable to numerous tissue engineering and regenerative medicine applications.

Collagen I foams are used in the clinic as scaffolds to promote articular cartilage repair as they provide a bioactive environment for cells with chondrogenic potential. However, collagen I as a base material does not allow for precise control over bioactivity. Alternatively, recombinant bacterial collagens can be used as “blank slate” collagen molecules to offer a versatile platform for incorporation of selected bioactive sequences and fabrication into 3D scaffolds. Here, we show the potential of Streptococcal collagen-like 2 (Scl2) protein foams modified with peptides designed to specifically and noncovalently bind hyaluronic acid and chondroitin sulfate to improve chondrogenesis of human mesenchymal stem cells (hMSCs) compared to collagen I foams. Specific compositions of functionalized Scl2 foams lead to improved chondrogenesis compared to both nonfunctionalized Scl2 and collagen I foams, as indicated by gene expression, extracellular matrix accumulation, and compression moduli. hMSCs cultured in functionalized Scl2 foams exhibit decreased collagens I and X gene and protein expression, suggesting an advantage over collagen I foams in promoting a chondrocytic phenotype. These highly modular foams can be further modified to improve specific aspects chondrogenesis. As such, these scaffolds also have the potential to be tailored for other regenerative medicine applications.

Polyetheretherketone (PEEK) is a high performance polymer, with high melting temperature and high resistance to wear. PEEK biomedical devices are typically manufactured to produce nonflexible structures. In this study, we fabricated flexible PEEK scaffolds from multifilament and monofilament yarns, using weaving technologies. Scaffolds were compared for structural and mechanical properties, and assessed for in vitro biological response to L929 mouse fibroblast cells. PEEK scaffolds were found to support fibroblast cell attachment and proliferation, with similar cell numbers to a polyethylene terephthalate scaffold. The large pores (261–280 μm) of the monofilament scaffold prevented pore coverage by cells, confining cells to filaments, whereas the smaller pores (81–100 μm) of the multifilament scaffold permitted partial pore coverage. Poor cell adhesion, due to large filament curvature angles, created a checkered pattern on the woven surface, a previously undocumented phenomenon. The multifilament scaffold was found to be lighter, thinner, and less porous, with better mechanical properties (load at break: 657 N, elastic recovery: 66%, burst strength: 492 N) than the monofilament scaffold (load at break: 534 N, elastic recovery: 30%, burst strength: 401 N). Results indicate that flexible PEEK woven structures may find application as tissue engineering scaffolds, particularly for engineering soft tissues. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3326–3331, 2012.

We describe the development of a highly elastic and adhesive surgical tissue sealant, based on photochemically crosslinked gelatin, for sealing sutured incisions in the gastrointestinal (GI) tract in a rabbit surgical model and in a canine colon anastomosis study. The study included in vitro assessment of mechanical parameters of the tissue sealant and in vivo analysis of burst strength and histology at 24 h, 3 days and 7 days post surgery, in a rabbit model, to assess progress of wound healing at the suture sites. Utility of this sealant to repair and seal a lower colonic resection and anastomosis procedure in a canine model was also investigated. We show that a photopolymerised gelatin tissue sealant provides effective sealing of GI incisions and facilitates wound healing with no evidence of inflammation up to 28 days post-surgery. Blending of derivatised gelatin with underivatised gelatin allowed tuning of elasticity and elastic modulus of the photopolymerised sealant to suit surgical applications. High tissue adhesive strength was maintained at all blend ratios and exceeded 100 kPa. This highly elastic and adhesive photopolymerised gelatin tissue sealant offers a number of advantages over currently available sealants suitable for GI surgical procedures.

Gelatin is widely used as a medical biomaterial because it is readily available, cheap, biodegradable and demonstrates favourable biocompatibility. Many applications require stabilisation of the biomaterial by chemical crosslinking, and this often involves derivatisation of the protein or treatment with cytotoxic crosslinking agents. We have previously shown that a facile photochemical method, using blue light, a ruthenium catalyst and a persulphate oxidant, produces covalent di-tyrosine crosslinks in resilin and fibrinogen to form stable hydrogel biomaterials. Here we show that various gelatins can also be rapidly crosslinked to form highly elastic (extension to break >650%) and adhesive (stress at break >100 kPa) biomaterials. Although the method does not require derivatisation of the protein, we show that when the phenolic (tyrosine-like) content of gelatin is increased, the crosslinked material becomes resistant to swelling, yet retains considerable elasticity and high adhesive strength. The reagents are not cytotoxic at the concentration used in the photopolymerisation reaction. When tested in vivo in sheep lung, the photopolymerised gelatin effectively sealed a wound in lung tissue from blood and air leakage, was not cytotoxic and did not produce an inflammatory response. The elastic properties, thermal stability, speed of curing and high tissue adhesive strength of this photopolymerised gelatin, offer considerable improvement over current surgical tissue sealants.