Intrarenal pressure with hand-pump or pressurized-bag irrigation: randomized clinical trial at retrograde intrarenal surgery.

BACKGROUND: The aim was to ascertain the impact of irrigation technique on human intrarenal pressure during retrograde intrarenal surgery. METHODS: A parallel randomized trial recruited patients across three hospital sites. Patients undergoing retrograde intrarenal surgery for renal stone treatment with an 11/13-Fr ureteral access sheath were allocated randomly to 100 mmHg pressurized-bag (PB) or manual hand-pump (HP) irrigation. The primary outcome was mean procedural intrarenal pressure. Secondary outcomes included maximum intrarenal pressure, variance, visualization, HP force of usage, procedure duration, stone clearance, and clinical outcomes. Live intrarenal pressure monitoring was performed using a COMETTMII pressure guidewire, deployed cystoscopically to the renal pelvis. The operating team was blinded to the intrarenal pressure. RESULTS: Thirty-eight patients were randomized between July and November 2023 (trial closure). The final analysis included 34 patients (PB 16; HP 18). Compared with PB irrigation, HP irrigation resulted in significantly higher mean intrarenal pressure (mean(s.d.) 62.29(27.45) versus 38.16(16.84) mmHg; 95% c.i. for difference in means (MD) 7.97 to 40.29 mmHg; P = 0.005) and maximum intrarenal pressure (192.71(106.23) versus 68.04(24.16) mmHg; 95% c.i. for MD 70.76 to 178.59 mmHg; P < 0.001), along with greater variance in intrarenal pressure (log transformed) (6.23(1.59) versus 4.60(1.30); 95% c.i. for MD 0.62 to 2.66; P = 0.001). Surgeon satisfaction with procedural vision reported on a scale of 10 was higher with PB compared with HP irrigation (mean(s.d.) 8.75(0.58) versus 6.28(1.27); 95% c.i. for MD 1.79 to 3.16; P < 0.001). Subjective HP usage force did not correlate significantly with transmitted intrarenal pressure (Pearson R = -0.15, P = 0.57). One patient (HP arm) developed urosepsis. CONCLUSION: Manual HP irrigation resulted in higher and more fluctuant intrarenal pressure trace (with inferior visual clarity) than 100-mmHg PB irrigation. REGISTRATION NUMBER: osf.io/jmg2h (https://osf.io/).

Optimizing the Delivery of mRNA to Mesenchymal Stem Cells for Tissue Engineering Applications.

Messenger RNA (mRNA) represents a promising therapeutic tool in the field of tissue engineering for the fast and transient production of growth factors to support new tissue regeneration. However, one of the main challenges to optimizing its use is achieving efficient uptake and delivery to mesenchymal stem cells (MSCs), which have been long reported as difficult-to-transfect. The aim of this study was to systematically screen a range of nonviral vectors to identify optimal transfection conditions for mRNA delivery to MSCs. Furthermore, for the first time, we wanted to directly compare the protein expression profile from three different types of mRNA, namely, unmodified mRNA (uRNA), base-modified mRNA (modRNA), and self-amplifying mRNA (saRNA) in MSCs. A range of polymer- and lipid-based vectors were used to encapsulate mRNA and directly compared in terms of physicochemical properties as well as transfection efficiency and cytotoxicity in MSCs. We found that both lipid- and polymer-based materials were able to successfully condense and encapsulate mRNA into nanosized particles (<200 nm). The overall charge and encapsulation efficiency of the nanoparticles was dependent on the vector type as well as the vector:mRNA ratio. When screened in vitro, lipid-based vectors proved to be superior in terms of mRNA delivery to MSCs cultured in a 2D monolayer and from a 3D collagen-based scaffold with minimal effects on cell viability, thus opening the potential for scaffold-based mRNA delivery. Modified mRNA consistently showed the highest levels of protein expression in MSCs, demonstrating 1.2-fold and 5.6-fold increases versus uRNA and saRNA, respectively. In summary, we have fully optimized the nonviral delivery of mRNA to MSCs, determined the importance of careful selection of the mRNA type used, and highlighted the strong potential of mRNA for tissue engineering applications.

The Development of Principles for Patient and Public Involvement (PPI) in Preclinical Spinal Cord Research: A Modified Delphi Study.

INTRODUCTION: There is currently limited guidance for researchers on Patient and Public Involvement (PPI) for preclinical spinal cord research, leading to uncertainty about design and implementation. This study aimed to develop evidence-informed principles to support preclinical spinal cord researchers to incorporate PPI into their research. METHODS: This study used a modified Delphi method with the aim of establishing consensus on a set of principles for PPI in spinal cord research. Thirty-eight stakeholders including researchers, clinicians and people living with spinal cord injury took part in the expert panel. Participants were asked to rate their agreement with a series of statements relating to PPI in preclinical spinal cord research over two rounds. As part of Round 2, they were also asked to rate statements as essential or desirable. RESULTS: Thirty-eight statements were included in Round 1, after which five statements were amended and two additional statements were added. After Round 2, consensus (> 75% agreement) was reached for a total of 27 principles, with 13 rated as essential and 14 rated as desirable. The principles with highest agreement related to diversity in representation among PPI contributors, clarity of the purpose of PPI and effective communication. CONCLUSION: This research developed a previously unavailable set of evidence-informed principles to inform PPI in preclinical spinal cord research. These principles provide guidance for researchers seeking to conduct PPI in preclinical spinal cord research and may also inform PPI in other preclinical disciplines. PATIENT AND PUBLIC INVOLVEMENT STATEMENT: This study was conducted as part of a project aiming to develop PPI in preclinical spinal cord injury research associated with an ongoing research collaboration funded by the Irish Rugby Football Union Charitable Trust (IRFU CT) and the Science Foundation Ireland Centre for Advanced Materials and BioEngineering Research (SFI AMBER), with research conducted by the Tissue Engineering Research Group (TERG) at the RCSI University of Medicine and Health Sciences. The project aims to develop an advanced biomaterials platform for spinal cord repair and includes a PPI Advisory Panel comprising researchers, clinicians and seriously injured rugby players to oversee the work of the project. PPI is included in this study through the involvement of members of the PPI Advisory Panel in the conceptualisation of this research, review of findings, identification of key points for discussion and preparation of the study manuscript as co-authors.

Upper urinary tract pressures in endourology: a systematic review of range, variables and implications.

OBJECTIVES: To systematically review the literature to ascertain the upper tract pressures generated during endourology, the relevant influencing variables and clinical implications. MATERIALS AND METHODS: A systematic review of the MEDLINE, Scopus and Cochrane databases was performed by two authors independently (S.C., N.D.). Studies reporting ureteric or intrarenal pressures (IRP) during semi-rigid ureteroscopy (URS)/flexible ureterorenoscopy (fURS)/percutaneous nephrolithotomy (PCNL)/miniaturized PCNL (mPCNL) in the period 1950-2021 were identified. Both in vitro and in vivo studies were considered for inclusion. Findings were independently screened for eligibility based on content, with disagreements resolved by author consensus. Data were assessed for bias and compiled based on predefined variables. RESULTS: Fifty-two studies met the inclusion criteria. Mean IRP appeared to frequently exceed a previously proposed threshold of 40 cmH2 O. Semi-rigid URS with low-pressure irrigation (gravity <1 m) resulted in a wide mean IRP range (lowest reported 6.9 cmH2 O, highest mean 149.5 ± 6.2 cmH2 O; animal models). The lowest mean observed with fURS without a ureteric access sheath (UAS) was 47.6 ± 4.1 cmH2 O, with the maximum peak IRP being 557.4 cmH2 O (in vivo human data). UAS placement significantly reduced IRP during fURS, but did not guarantee pressure control with hand-operated pump/syringe irrigation. Miniaturization of PCNL sheaths was associated with increased IRP; however, a wide mean human IRP range has been recorded with both mPCNL (lowest -6.8 ± 2.2 cmH2 O [suction sheath]; highest 41.2 ± 5.3 cmH2 O) and standard PCNL (lowest 6.5 cmH2 O; highest 41.2 cmH2 O). Use of continuous suction in mPCNL results in greater control of mean IRP, although short pressure peaks >40 cmH2 O are not entirely prevented. Definitive conclusions are limited by heterogeneity in study design and results. Postoperative pain and pyrexia may be correlated with increased IRP, however, few in vivo studies correlate clinical outcome with measured IRP. CONCLUSIONS: Intrarenal pressure generated during upper tract endoscopy often exceeds 40 cmH2 O. IRP is multifactorial in origin, with contributory variables discussed. Larger prospective human in vivo studies are required to further our understanding of IRP thresholds and clinical sequelae.

In vivo ureteroscopic intrarenal pressures and clinical outcomes: a multi-institutional analysis of 120 consecutive patients.

OBJECTIVES: To evaluate the pressure range generated in the human renal collecting system during ureteroscopy (URS), in a large patient sample, and to investigate a relationship between intrarenal pressure (IRP) and outcome. PATIENTS AND METHODS: A prospective multi-institutional study was conducted, with ethics board approval; February 2022-March 2023. Recruitment was of 120 consecutive consenting adult patients undergoing semi-rigid URS and/or flexible ureterorenoscopy (FURS) for urolithiasis or diagnostic purposes. Retrograde, fluoroscopy-guided insertion of a 0.036-cm (0.014″) pressure guidewire (COMET™ II, Boston Scientific, Marlborough, MA, USA) to the renal pelvis was performed. Baseline and continuous ureteroscopic IRP was recorded, alongside relevant operative variables. A 30-day follow-up was completed. Descriptive statistics were applied to IRP traces, with mean (sd) and maximum values and variance reported. Relationships between IRP and technical variables, and IRP and clinical outcome were interrogated using the chi-square test and independent samples t-test. RESULTS: A total of 430 pressure traces were analysed from 120 patient episodes. The mean (sd) baseline IRP was 16.45 (5.99) mmHg and the intraoperative IRP varied by technique. The mean (sd) IRP during semi-rigid URS with gravity irrigation was 34.93 (11.66) mmHg. FURS resulted in variable IRP values: from a mean (sd) of 26.78 (5.84) mmHg (gravity irrigation; 12/14-F ureteric access sheath [UAS]) to 87.27 (66.85) mmHg (200 mmHg pressurised-bag irrigation; 11/13-F UAS). The highest single pressure peak was 334.2 mmHg, during retrograde pyelography. Six patients (5%) developed postoperative urosepsis; these patients had significantly higher IRPs during FURS (mean [sd] 81.7 [49.52] mmHg) than controls (38.53 [22.6] mmHg; P < 0.001). CONCLUSIONS: A dynamic IRP profile is observed during human in vivo URS, with IRP frequently exceeding expected thresholds. A relationship appears to exist between elevated IRP and postoperative urosepsis.

Applying Patient and Public Involvement in preclinical research: A co-created scoping review.

BACKGROUND: Patient and Public Involvement (PPI) in research aims to improve the quality, relevance and appropriateness of research. PPI has an established role in clinical research where there is evidence of benefit, and where policymakers and funders place continued emphasis on its inclusion. However, for preclinical research, PPI has not yet achieved the same level of integration. As more researchers, including our team, aim to include PPI in preclinical research, the development of an evidence-based approach is important. Therefore, this scoping review aimed to identify and map studies where PPI has been used in preclinical research and develop principles that can be applied in other projects. METHODS: A scoping review was conducted to search the literature in Medline (PubMed), EMBASE, CINAHL, PsycInfo and Web of Science Core Collection to identify applied examples of preclinical PPI. Two independent reviewers conducted study selection and data extraction separately. Data were extracted relating to PPI in terms of (i) rationale and aims, (ii) approach used, (iii) benefits and challenges, (iv) impact and evaluation and (v) learning opportunities for preclinical PPI. Findings were reviewed collaboratively by PPI contributors and the research team to identify principles that could be applied to other projects. RESULTS: Nine studies were included in the final review with the majority of included studies reporting PPI to improve the relevance of their research, using approaches such as PPI advisory panels and workshops. Researchers report several benefits and challenges, although evidence of formal evaluation is limited. CONCLUSION: Although currently there are few examples of preclinical research studies reporting empirical PPI activity, their findings may support those aiming to use PPI in preclinical research. Through collaborative analysis of the scoping review findings, several principles were developed that may be useful for other preclinical researchers. PATIENT OR PUBLIC CONTRIBUTION: This study was conducted as part of a broader project aiming to develop an evidence base for preclinical PPI that draws on a 5-year preclinical research programme focused on the development of advanced biomaterials for spinal cord repair as a case study. A PPI Advisory Panel comprising seriously injured rugby players, clinicians, preclinical researchers and PPI facilitators collaborated as co-authors on the conceptualization, execution and writing of this review, including refining the findings into the set of principles reported here.

Development of a Gene-Activated Scaffold Incorporating Multifunctional Cell-Penetrating Peptides for pSDF-1α Delivery for Enhanced Angiogenesis in Tissue Engineering Applications.

Non-viral gene delivery has become a popular approach in tissue engineering, as it permits the transient delivery of a therapeutic gene, in order to stimulate tissue repair. However, the efficacy of non-viral delivery vectors remains an issue. Our lab has created gene-activated scaffolds by incorporating various non-viral delivery vectors, including the glycosaminoglycan-binding enhanced transduction (GET) peptide into collagen-based scaffolds with proven osteogenic potential. A modification to the GET peptide (FLR) by substitution of arginine residues with histidine (FLH) has been designed to enhance plasmid DNA (pDNA) delivery. In this study, we complexed pDNA with combinations of FLR and FLH peptides, termed GET* nanoparticles. We sought to enhance our gene-activated scaffold platform by incorporating GET* nanoparticles into collagen-nanohydroxyapatite scaffolds with proven osteogenic capacity. GET* N/P 8 was shown to be the most effective formulation for delivery to MSCs in 2D. Furthermore, GET* N/P 8 nanoparticles incorporated into collagen-nanohydroxyapatite (coll-nHA) scaffolds at a 1:1 ratio of collagen:nanohydroxyapatite was shown to be the optimal gene-activated scaffold. pDNA encoding stromal-derived factor 1α (pSDF-1α), an angiogenic chemokine which plays a role in BMP mediated differentiation of MSCs, was then delivered to MSCs using our optimised gene-activated scaffold platform, with the aim of significantly increasing angiogenesis as an important precursor to bone repair. The GET* N/P 8 coll-nHA scaffolds successfully delivered pSDF-1α to MSCs, resulting in a significant, sustained increase in SDF-1α protein production and an enhanced angiogenic effect, a key precursor in the early stages of bone repair.

Impact of Fluid Flow Shear Stress on Osteoblast Differentiation and Cross-Talk with Articular Chondrocytes.

Bone cells, in particular osteoblasts, are capable of communication with each other during bone growth and homeostasis. More recently it has become clear that they also communicate with other cell-types; including chondrocytes in articular cartilage. One way that this process is facilitated is by interstitial fluid movement within the pericellular and extracellular matrices. This stimulus is also an important mechanical signal in skeletal tissues, and is known to generate shear stresses at the micron-scale (known as fluid flow shear stresses (FFSS)). The primary aim of this study was to develop and characterize an in vitro bone-cartilage crosstalk system, to examine the effect of FFSS on these cell types. Specifically, we evaluated the response of osteoblasts and chondrocytes to FFSS and the effect of FFSS-induced soluble factors from the former, on the latter. This system will ultimately be used to help us understand the role of subchondral bone damage in articular cartilage degeneration. We also carried out a comparison of responses between cell lines and primary murine cells in this work. Our findings demonstrate that primary cells produce a more reliable and reproducible response to FFSS. Furthermore we found that at lower magnitudes , direct FFSS produces anabolic responses in both chondrocytes and osteoblasts, whereas higher levels produce more catabolic responses. Finally we show that exposure to osteoblast-derived factors in conditioned media experiments produced similarly catabolic changes in primary chondrocytes.

SDF-1α gene-activated collagen scaffold drives functional differentiation of human Schwann cells for wound healing applications.

Enhancing angiogenesis is the prime target of current biomaterial-based wound healing strategies. However, these approaches largely overlook the angiogenic role of the cells of the nervous system. Therefore, we explored the role of a collagen-chondroitin sulfate scaffold functionalized with a proangiogenic gene stromal-derived factor-1α (SDF-1α)-an SDF-1α gene-activated scaffold on the functional regulation of human Schwann cells (SCs). A preliminary 2D study was conducted by delivering plasmids encoding for the SDF-1α gene into a monolayer of SCs using polyethyleneimine-based nanoparticles. The delivery of the SDF-1α gene into the SCs enhanced the production of proangiogenic vascular endothelial growth factor (VEGF). Subsequently, we investigated the impact of SDF-1α gene-activated scaffold (3D) on the SCs for 2 weeks, using a gene-free scaffold as control. The transfection of the SCs within the gene-activated scaffold resulted in transient overexpression of SDF-1α transcripts and triggered the production of bioactive VEGF that enhanced endothelial angiogenesis. The overexpression of SDF-1α also caused transient activation of the transcription factor c-Jun and supported the differentiation of SCs towards a repair phenotype. This was characterized by elevated expression of neurotrophin receptor p75NGFR. During this developmental stage, the SCs also performed an extensive remodelling of the basement matrix (fibronectin, collagen IV, and laminin) to enrich their environment with the pro-neurogenic matrix protein laminin, revealing an enhanced pro-neurogenic behavior. Together, this study shows that SDF-1α gene-activated scaffold is a highly bioinstructive scaffold capable of enhancing proangiogenic regenerative response in human SCs for improved wound healing.

Contemporary trends for urological training and management of stress urinary incontinence in Ireland.

INTRODUCTION AND HYPOTHESIS: The aim of this study is to evaluate the trends in stress urinary incontinence (SUI) surgery since the 2018 pause on use of the polypropylene (PP) mid-urethral sling (MUS) and to quantify the effect this has had on surgical training. METHODS: Two anonymous surveys were sent to all current urology trainees and to all consultant surgeons who specialise in stress urinary incontinence surgery. RESULTS: Prior to the pause, 86% (6 out of 7) of consultant urologists and 73% (11 out of 15) of consultant gynaecologists would "always"/"often" perform MUS for SUI. After that, 100% (22 out of 22) of consultants reported that they "never" perform MUS. There has been a modest increase in the use of urethral bulking agent (UBA) procedures among urologists, with 43% (3 out of 7) now "often" performing this, compared with 71% (5 out of 7) "never" performing it pre-2018. Trainee exposure to SUI surgery reduced by 75% between 2016 and 2020. Despite a ten-fold increase in UBA procedures logged by trainees, the decline in MUS has resulted in a major reduction in total SUI surgeries. Coinciding with this decrease in surgeries, there was a 56% reduction in trainees' self-assessed competence at SUI surgery. Thirteen percent of trainees are interested in specialising in Female Urology and those trainees had significantly greater exposure to SUI procedures during their training than those who did not (p = 0.0072). CONCLUSIONS: This study has identified a downward trend in SUI surgery, which is concerning for the undertreatment of females with SUI. A decline in SUI surgery training has resulted in reduced trainee confidence and interest in this subspecialty.

Comparison of synthetic mesh erosion and chronic pain rates after surgery for pelvic organ prolapse and stress urinary incontinence: a systematic review.

BACKGROUND: The aim of this study is to systematically compare rates of erosion and chronic pain after mesh insertion for pelvic organ prolapse (POP) and stress urinary incontinence (SUI) surgery. METHODS: A systematic electronic search was performed on studies that evaluated the incidence of erosion and chronic pain after mesh insertion for POP or SUI. The primary outcome measurement was to compare mesh erosion rates for POP and SUI surgery. Secondary outcome measurements were incidence of de novo pain and a comparison of patient demographics for both surgeries. RESULTS: Twenty-six studies on 292,606 patients (n = 9077 for POP surgery and n = 283,529 for SUI surgery) met the inclusion criteria. Median follow-up was 26.38 ± 22.17 months for POP surgery and 39.33 ± 27.68 months for SUI surgery. Overall, the POP group were older (p < 0.0001) and had a lower BMI (p < 0.0001). Mesh erosion rates were significantly greater in the POP group compared to the SUI group (4% versus 1.9%) (OR 2.13; 95% CI 1.91-2.37; p < 0.0001). The duration from surgery to onset of mesh erosion was 306.84 ± 183.98 days. There was no difference in erosion rates between abdominal and transvaginal mesh for POP. There was no difference in erosion rates between the transobturator and retropubic approach for SUI. The incidence of chronic pain was significantly greater in the POP group compared to the SUI group (6.7% versus 0.6%) (OR 11.02; 95% CI 8.15-14.9; p < 0.0001). The duration from surgery to onset of chronic pain was 325.88 ± 226.31 days. CONCLUSIONS: The risk of mesh erosion and chronic pain is significantly higher after surgery for POP compared to SUI. These significant complications occur within the first year after surgery.

Substrate Stiffness Modulates the Crosstalk Between Mesenchymal Stem Cells and Macrophages.

Upon implantation of a biomaterial, mesenchymal stem cells (MSCs) and macrophages contribute to the wound healing response and the regeneration cascade. Although biomaterial properties are known to direct MSC differentiation and macrophage polarization, the role of biomaterial cues, specifically stiffness, in directing the crosstalk between the two cell types is still poorly understood. This study aimed to elucidate the role of substrate stiffness in modulating the immunomodulatory properties of MSCs and to shed light on their complex interactions with macrophages when presented with diverse biomaterial stiffness cues, a situation analogous to the implant environment where multiple cell types interact with an implanted biomaterial to determine regenerative outcomes. We show that MSCs do not play an immunomodulatory role in the absence of an inflammatory stimulus. Using collagen-coated polyacrylamide gels of varying stiffness values, we demonstrate that the immunomodulatory capability of MSCs in the presence of an inflammatory stimulus is not dependent on the stiffness of the underlying substrate. Moreover, using paracrine and direct contact culture models, we show that a bidirectional crosstalk between MSCs and macrophages is necessary for promoting anti-inflammatory responses and positive immunomodulation, which is dependent on the stiffness of the underlying substrate. We finally show that direct cell-cell contact is not essential for this effect, with paracrine interactions promoting immunomodulatory interactions between MSCs and macrophages. Together, these results demonstrate that biophysical cues such as stiffness that are presented by biomaterials can be tuned to promote positive interactions between MSCs and macrophages which can in turn direct the downstream regenerative response.

SDF-1α gene-activated collagen scaffold enhances provasculogenic response in a coculture of human endothelial cells with human adipose-derived stromal cells.

Novel biomaterials can be used to provide a better environment for cross talk between vessel forming endothelial cells and wound healing instructor stem cells for tissue regeneration. This study seeks to investigate if a collagen scaffold containing a proangiogenic gene encoding for the chemokine stromal-derived factor-1 alpha (SDF-1α GAS) could be used to enhance functional responses in a coculture of human umbilical vein endothelial cells (HUVECs) and human adipose-derived stem/stromal cells (ADSCs). Functional responses were determined by (1) monitoring the amount of junctional adhesion molecule VE-cadherin released during 14 days culture, (2) expression of provasculogenic genes on the 14th day, and (3) the bioactivity of secreted factors on neurogenic human Schwann cells. When we compared our SDF-1α GAS with a gene-free scaffold, the results showed positive proangiogenic determination characterized by a transient yet controlled release of the VE-cadherin. On the 14th day, the coculture on the SDF-1α GAS showed enhanced maturation than its gene-free equivalent through the elevation of provasculogenic genes (SDF-1α-7.4-fold, CXCR4-1.5-fold, eNOS-1.5-fold). Furthermore, we also found that the coculture on SDF-1α GAS secretes bioactive factors that significantly (p < 0.01) enhanced human Schwann cells' clustering to develop toward Bünger band-like structures. Conclusively, this study reports that SDF-1α GAS could be used to produce a bioactive vascularized construct through the enhancement of the cooperative effects between endothelial cells and ADSCs.

The development of natural polymer scaffold-based therapeutics for osteochondral repair.

Due to the limited regenerative capacity of cartilage, untreated joint defects can advance to more extensive degenerative conditions such as osteoarthritis. While some biomaterial-based tissue-engineered scaffolds have shown promise in treating such defects, no scaffold has been widely accepted by clinicians to date. Multi-layered natural polymer scaffolds that mimic native osteochondral tissue and facilitate the regeneration of both articular cartilage (AC) and subchondral bone (SCB) in spatially distinct regions have recently entered clinical use, while the transient localized delivery of growth factors and even therapeutic genes has also been proposed to better regulate and promote new tissue formation. Furthermore, new manufacturing methods such as 3D bioprinting have made it possible to precisely tailor scaffold micro-architectures and/or to control the spatial deposition of cells in requisite layers of an implant. In this way, natural and synthetic polymers can be combined to yield bioactive, yet mechanically robust, cell-laden scaffolds suitable for the osteochondral environment. This mini-review discusses recent advances in scaffolds for osteochondral repair, with particular focus on the role of natural polymers in providing regenerative templates for treatment of both AC and SCB in articular joint defects.

The Incorporation of Marine Coral Microparticles into Collagen-Based Scaffolds Promotes Osteogenesis of Human Mesenchymal Stromal Cells via Calcium Ion Signalling.

Composite biomaterial scaffolds consisting of natural polymers and bioceramics may offer an alternative to autologous grafts for applications such as bone repair. Herein, we sought to investigate the possibility of incorporating marine coral microparticles into a collagen-based scaffold, a process which we hypothesised would enhance the mechanical properties of the scaffold as well its capacity to promote osteogenesis of human mesenchymal stromal cells. Cryomilling and sieving were utilised to achieve coral microparticles of mean diameters 14 µm and 64 µm which were separately incorporated into collagen-based slurries and freeze-dried to form porous scaffolds. X-ray diffraction and Fourier transform infrared spectroscopy determined the coral microparticles to be comprised of calcium carbonate whereas collagen/coral composite scaffolds were shown to have a crystalline calcium ethanoate structure. Crosslinked collagen/coral scaffolds demonstrated enhanced compressive properties when compared to collagen only scaffolds and also promoted more robust osteogenic differentiation of mesenchymal stromal cells, as indicated by increased expression of bone morphogenetic protein 2 at the gene level, and enhanced alkaline phosphatase activity and calcium accumulation at the protein level. Only subtle differences were observed when comparing the effect of coral microparticles of different sizes, with improved osteogenesis occurring as a result of calcium ion signalling delivered from collagen/coral composite scaffolds. These scaffolds, fabricated from entirely natural sources, therefore show promise as novel biomaterials for tissue engineering applications such as bone regeneration.

Staphylococcal Osteomyelitis: Disease Progression, Treatment Challenges, and Future Directions.

Osteomyelitis is an inflammatory bone disease that is caused by an infecting microorganism and leads to progressive bone destruction and loss. The most common causative species are the usually commensal staphylococci, with Staphylococcus aureus and Staphylococcus epidermidis responsible for the majority of cases. Staphylococcal infections are becoming an increasing global concern, partially due to the resistance mechanisms developed by staphylococci to evade the host immune system and antibiotic treatment. In addition to the ability of staphylococci to withstand treatment, surgical intervention in an effort to remove necrotic and infected bone further exacerbates patient impairment. Despite the advances in current health care, osteomyelitis is now a major clinical challenge, with recurrent and persistent infections occurring in approximately 40% of patients. This review aims to provide information about staphylococcus-induced bone infection, covering the clinical presentation and diagnosis of osteomyelitis, pathophysiology and complications of osteomyelitis, and future avenues that are being explored to treat osteomyelitis.

Raman spectroscopy predicts the link between claw keratin and bone collagen structure in a rodent model of oestrogen deficiency.

Osteoporosis is a common disease characterised by reduced bone mass and an increased risk of fragility fractures. Low bone mineral density is known to significantly increase the risk of osteoporotic fractures, however, the majority of non-traumatic fractures occur in individuals with a bone mineral density too high to be classified as osteoporotic. Therefore, there is an urgent need to investigate aspects of bone health, other than bone mass, that can predict the risk of fracture. Here, we successfully predicted association between bone collagen and nail keratin in relation to bone loss due to oestrogen deficiency using Raman spectroscopy. Raman signal signature successfully discriminated between ovariectomised rats and their sham controls with a high degree of accuracy for the bone (sensitivity 89%, specificity 91%) and claw tissue (sensitivity 89%, specificity 82%). When tested in an independent set of claw samples the classifier gave 92% sensitivity and 85% specificity. Comparison of the spectral changes occurring in the bone tissue with the changes occurring in the keratin showed a number of common features that could be attributed to common changes in the structure of bone collagen and claw keratin. This study established that systemic oestrogen deficiency mediates parallel structural changes in both the claw (primarily keratin) and bone proteins (primarily collagen). This strengthens the hypothesis that nail keratin can act as a surrogate marker of bone protein status where systemic processes induce changes.

Bioinspired Star-Shaped Poly(l-lysine) Polypeptides: Efficient Polymeric Nanocarriers for the Delivery of DNA to Mesenchymal Stem Cells.

The field of tissue engineering is increasingly recognizing that gene therapy can be employed for modulating in vivo cellular response thereby guiding tissue regeneration. However, the field lacks a versatile and biocompatible gene delivery platform capable of efficiently delivering transgenes to mesenchymal stem cells (MSCs), a cell type often refractory to transfection. Herein, we describe the extensive and systematic exploration of three architectural variations of star-shaped poly(l-lysine) polypeptide (star-PLL) with varying number and length of poly(l-lysine) arms as potential nonviral gene delivery vectors for MSCs. We demonstrate that star-PLL vectors are capable of self-assembling with pDNA to form stable, cationic nanomedicines. Utilizing high content screening, live cell imaging, and mechanistic uptake studies we confirm the intracellular delivery of pDNA by star-PLLs to MSCs is a rapid process, which likely proceeds via a clathrin-independent mechanism. We identify a star-PLL composition with 64 poly(l-lysine) arms and five l-lysine subunits per arm as a particularly efficient vector that is capable of delivering both reporter genes and the therapeutic transgenes bone morphogenetic protein-2 and vascular endothelial growth factor to MSCs. This composition facilitated a 1000-fold increase in transgene expression in MSCs compared to its linear analogue, linear poly(l-lysine). Furthermore, it demonstrated comparable transgene expression to the widely used vector polyethylenimine using a lower pDNA dose with significantly less cytotoxicity. Overall, this study illustrates the ability of the star-PLL vectors to facilitate efficient, nontoxic nucleic acid delivery to MSCs thereby functioning as an innovative nanomedicine platform for tissue engineering applications.

A Short History of Bioengineering Research in Ireland.

In July 2018, Ireland will host the World Congress of Biomechanics in Dublin. This Congress is held once every 4 yr and is the premier meeting worldwide in its field, with over 3000 people expected to visit Dublin in July. The awarding of the 2018 Congress to Ireland is a reflection of the strength of biomechanics and bioengineering research in this country. To mark this event, herein we describe the development of biomechanics and bioengineering research in Ireland over the past 40 yr, which has grown in parallel with the medical device industry as well as the expansion of Government investment in science, innovation, and a knowledge-based economy. The growth of this activity has resulted in Ireland becoming established as a global hub in the field.

Differentiation of Vascular Stem Cells Contributes to Ectopic Calcification of Atherosclerotic Plaque.

The cellular and molecular basis of vascular calcification (VC) in atherosclerosis is not fully understood. Here, we investigate role of resident/circulating progenitor cells in VC and contribution of inflammatory plaque environment to this process. Vessel-derived stem/progenitor cells (VSCs) and mesenchymal stem cells (MSCs) isolated from atherosclerotic ApoE(-/-) mice showed significantly more in vitro osteogenesis and chondrogenesis than cells generated from control C57BL/6 mice. To assess their ability to form bone in vivo, cells were primed chondrogenically or cultured in control medium on collagen glycosaminoglycan scaffolds in vitro prior to subcutaneous implantation in ApoE(-/-) and C57BL/6 mice using a crossover study design. Atherosclerotic ApoE(-/-) MSCs and VSCs formed bone when implanted in C57BL/6 mice. In ApoE(-/-) mice, these cells generated more mature bone than C57BL/6 cells. The atherosclerotic in vivo environment alone promoted bone formation by implanted C57BL/6 cells. Un-primed C57BL/6 VSCs were unable to form bone in either mouse strain. Treatment of ApoE(-/-) VSC chondrogenic cultures with interleukin (IL)-6 resulted in significantly increased glycosaminoglycan deposition and expression of characteristic chondrogenic genes at 21 days. In conclusion, resident vascular cells from atherosclerotic environment respond to the inflammatory milieu and undergo calcification. IL-6 may have a role in aberrant differentiation of VSCs contributing to vascular calcification in atherosclerosis.