Rotator cuff tears are common in middle-aged and elderly patients. Despite advances in the surgical repair of rotator cuff tears, the rates of recurrent tear remain high. This may be due to the complexity of the tendons of the rotator cuff, which contributes to an inherently hostile healing environment. During the past 20 years, there has been an increased interest in the use of biologics to complement the healing environment in the shoulder, in order to improve rotator cuff healing and reduce the rate of recurrent tears. The aim of this review is to provide a summary of the current evidence for the use of forms of biological augmentation when repairing rotator cuff tears.

Cite this article: Bone Joint J 2024;106-B(9):978–985.

Aims

This study aimed to determine the expression and clinical significance of a cartilage protein, cartilage oligomeric matrix protein (COMP), in knee osteoarthritis (OA) patients.

Introduction. Autologous Matrix Induced Chondrogenesis (AMIC) for surgical treatment of osteochondral lesions of the talus (OCLT) has shown excellent clinical and radiological results at short term follow up two years after surgery. However, no mid-term follow up data is available. Aim. 1. To evaluate the clinical outcome after AMIC-aided reconstruction of osteochondral lesions of the talus at a minimum follow up time of five years. 2. To evaluate the morphology and quality of the regenerated cartilage by magnetic resonance imaging (MRI) at on at a minimum follow up time of five years. Methods. Seventeen patients prospectively underwent surgery receiving a AMIC-aided repair of OCLT consisting of debridement, autologous grafting, and sealing of the defect with a collagen scaffold (Chondro-Gide, Geistlich Surgery, Wolhusen, Switzerland). Clinical and radiological assessment was performed before and after a minimum of 60 months after surgery (average 78 months, range, 60–120). Clinical examination included the American Orthopaedic Foot & Ankle Society (AOFAS) ankle score and the Visual Analogue Scale (VAS). Radiological imaging consisted of MRI. The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was applied. Results. The AOFAS ankle score improved significantly from a mean of 60 points preoperatively (range, 17–79) to 91 points (range, 70–100) postoperatively (p< 0.01). The preoperative pain score averaged a VAS of 5 (range, 2–8), improving to an average of 1.1 (range 0–8) (p< 0.01). The MOCART score for cartilage repair tissue on postoperative MRI averaged 71 points (range, 50–90). Conclusion. The AMIC-procedure is safe for the treatment of OCLT with overall good clinical and magnetic resonance imaging results at five years follow up

Bone morphogenetic proteins (BMPs) have been widely investigated for treating non-healing fractures. They participate in bone reconstruction by inducing osteoblast differentiation, and osteoid matrix production. 1. The human recombinant protein of BMP-7 was among the first growth factors approved for clinical use. Despite achieving comparable results to autologous bone grafting, severe side effects have been associated with its use. 2. Furthermore, BMP-7 was removed from the market. 3. These complications are related to the high doses used (1.5-40 miligrams per surgery). 2. compared to the physiological concentration of BMP in fracture healing (in the nanogram to picogram per milliliter range). 4. In this study, we use transcript therapy to deliver chemically modified mRNA (cmRNA) encoding BMP-7. Compared to direct use of proteins, transcript therapy allows the sustained synthesis of proteins with native conformation and true post-translational modifications using doses comparable to the physiological ones. 5. Moreover, cmRNA technology overcomes the safety and affordability limitations of standard gene therapy i.e. pDNA. 6. BMP-7 cmRNA was delivered using Lipofectamine™ MessengerMAX™ to human mesenchymal stromal cells (hMSCs). We assessed protein expression and osteogenic capacity of hMSCs in monolayer culture and in a house-made, collagen hydroxyapatite scaffold. Using fluorescently-labelled cmRNA we observed an even distribution after loading complexes into the scaffold and a complete release after 3 days. For both monolayer and 3D culture, BMP-7 production peaked at 24 hours post-transfection, however cells transfected in scaffolds showed a sustained expression. BMP-7 transfected hMSCs yielded significantly higher ALP activity and Alizarin red staining at later timepoints compared to the untransfected group. Interestingly, BMP-7 cmRNA treatment triggered expression of osteogenic genes like OSX, RUNX-2 and OPN, which was also reflected in immunostainings. This work highlights the relevance of cmRNA technology that may overcome the shortcomings of protein delivery while circumventing issues of traditional pDNA-based gene therapy for bone regeneration. Acknowledgement: This work has been performed as part of the cmRNAbone project and has received funding from the European Union's Horizon 2020 research and innovation programme under the Grant Agreement No 874790

Aims

Several artificial bone grafts have been developed but fail to achieve anticipated osteogenesis due to their insufficient neovascularization capacity and periosteum support. This study aimed to develop a vascularized bone-periosteum construct (VBPC) to provide better angiogenesis and osteogenesis for bone regeneration.

Abstract. Background. Autologous chondrocyte implantation is a NICE approved intervention however it involves the morbidity of two operations, a prolonged rehabilitation and substantial healthcare costs. This study describes a novel, one-step, bone marrow (BM) derived mesenchymal stem cell (MSC) transplantation technique for treating knee osteochondral lesions and presents our prospective clinical study investigating the success of this technique in 206 lesions over a 5 year period. Methodology. The surgical technique involves harvesting BM from patients’ anterior superior iliac spines, centrifugation to isolate MSCs and seeding into a type 1 collagen scaffold (SyngenitTM Biomatrix). Autologous fibrin glue is used to secure the scaffold into the defect. Inclusion criteria included patients aged 15 – 55 years old with symptomatic osteochondral lesions >1cm2. Exclusion criteria included patients with ligament instability, uncorrected alignment, inflammatory arthropathy and a Body Mass Index >35 kg/m2. Outcome measures included the Modified Cincinnati Knee Rating System (MCKRS), complications and reoperations. Results. Mean MCKR scores showed statistically significant improvements compared to pre-operative scores at 6 months 58.79 ± 3.5 and 1 year postoperatively 63.82 ± 3.93 with further improvements at 2 years and 5 years which did not reach statistical significance. Survival rates were 97.9%, 94% and 93.2% at 1, 2 and 5 years. Multiple regression analysis identified previous cartilage surgery, microfracture and age as factors affecting MCKRS scores (p < 0.029, 0.001 and 0.030, respectively). Conclusions. One-step BM derived stem cell transplantation demonstrates satisfactory outcomes over a 5 year period

Meniscus tears have been treated using partial meniscectomy to relieve pain in patients, although this leads to the onset of early osteoarthritis (OA). Cell-based therapies can help preserve the meniscus, although the presence of inflammatory cytokines compromises clinical outcomes. Anti-inflammatory drugs (e.g. celecoxib), can help to reduce pain in patients and in vitro studies suggest a beneficial effect on cytokine inhibited matrix content. Previously, we have demonstrated that the inhibitory effects of IL-1β can be countered by culture under low oxygen tension or physioxia. The present study sought to understand whether physioxia, celecoxib or combined application can counter the inhibitory effects IL-1β inhibited meniscus cells. Human avascular and vascular meniscus cells (n =3) were isolated and expanded under 20% (hyperoxia) or 2% (physioxia) oxygen. Cells were seeded into collagen scaffolds (Geistlich, Wolhusen) and cultured for 28 days either in the presence of 0.1ng/mL IL-1β, 5µg/mL celecoxib or both under their expansion oxygen conditions. Histological (DMMB, collagen I and collagen II immunostaining), GAG content and gene expression analysis was evaluated for the scaffolds. Under hyperoxia, meniscus cells showed a significant reduction in GAG content in the presence of IL-1β (*p < 0.05). Celecoxib alone did not significantly increase GAG content in IL-1β treated cultures. In contrast, physioxic culture showed a donor dependent increase in GAG content in control, IL-1β and celecoxib treated cultures with corresponding histological staining correlating with these results. Additionally, gene expression showed an upregulation in COL1A1, COL2A1 and ACAN and a downregulation in MMP13 and ADAMTS5 under physioxia for all experimental groups. Physioxia alone had a stronger effect in countering the inhibitory effects of IL-1β treated meniscus cells than celecoxib under hyperoxia. Preconditioning meniscus cells under physioxia prior to implantation has the potential to improve clinical outcomes for cell-based therapies of the meniscus

Restoration a joint's articular surface following degenerative or traumatic pathology to the osteochondral unit pose a significant challenge. Recent advances have shown the utility of collagen-based scaffolds in the regeneration of osteochondral tissue. To provide these collagen scaffolds with the appropriate superstructure novel techniques in 3D printing have been investigated. This study investigates the use of polyɛ-caprolactone (PCL) collagen scaffolds in a porcine cadaveric model to establish the stability of the biomaterial once implanted. This study was performed in a porcine cadaveric knee model. 8mm defects were created in the medial femoral trochlea and repaired with a PCL collagen scaffold. Scaffolds were secured by one of three designs; Press Fit (PF), Press Fit with Rings (PFR), Press Fit with Fibrin Glue (PFFG). Mobilisation was simulated by mounting the pig legs on a continuous passive motion (CPM) machine for either 50 or 500 cycles. Biomechanical tensile testing was performed to examine the force required to displace the scaffold. 18 legs were used (6 PF, 6 PFR, 6 PFFG). Fixation remained intact in 17 of the cohort (94%). None of the PF or PFFG scaffolds displaced after CPM cycling. Mean peak forces required to displace the scaffold were highest in the PFFG group (3.173 Newtons, Standard deviation = 1.392N). The lowest peak forces were observed in the PFR group (0.871N, SD = 0.412N), while mean peak force observed in the PF group was 2.436N (SD = 0.768). There was a significant difference between PFFG and PFR (p = 0.005). There was no statistical significance in the relationship between the other groups. PCL reinforcement of collagen scaffolds provide an innovative solution for improving stiffness of the construct, allowing easier handling for the surgeon. Increasing the stiffness of the scaffold also allows press fit solutions for reliable fixation. Press fit PCL collagen scaffolds with and without fibrin glue provide dependable stability. Tensile testing provides an objective analysis of scaffold fixation. Further investigation of PCL collagen scaffolds in a live animal model to establish quality of osteochondral tissue regeneration are required

Aims

This study compared patients who underwent arthroscopic repair of large to massive rotator cuff tears (LMRCTs) with isolated incomplete repair of the tear and patients with incomplete repair with biceps tendon augmentation. We aimed to evaluate the additional benefit on clinical outcomes and the capacity to lower the re-tear rate.

Aims

To determine the relationship between articular cartilage status and clinical outcomes after medial opening-wedge high tibial osteotomy (MOHTO) for medial compartmental knee osteoarthritis at intermediate follow-up.

Aims. Minimally manipulated cells, such as autologous bone marrow concentrates (BMC), have been investigated in orthopaedics as both a primary therapeutic and augmentation to existing restoration procedures. However, the efficacy of BMC in combination with tissue engineering is still unclear. In this study, we aimed to determine whether the addition of BMC to an osteochondral scaffold is safe and can improve the repair of large osteochondral defects when compared to the scaffold alone. Methods. The ovine femoral condyle model was used. Bone marrow was aspirated, concentrated, and used intraoperatively with a collagen/hydroxyapatite scaffold to fill the osteochondral defects (n = 6). Tissue regeneration was then assessed versus the scaffold-only group (n = 6). Histological staining of cartilage with alcian blue and safranin-O, changes in chondrogenic gene expression, microCT, peripheral quantitative CT (pQCT), and force-plate gait analyses were performed. Lymph nodes and blood were analyzed for safety. Results. The results six months postoperatively showed that there were no significant differences in bone regrowth and mineral density between BMC-treated animals and controls. A significant upregulation of messenger RNA (mRNA) for types I and II collagens in the BMC group was observed, but there were no differences in the formation of hyaline-like cartilage between the groups. A trend towards reduced sulphated glycosaminoglycans (sGAG) breakdown was detected in the BMC group but this was not statistically significant. Functional weightbearing was not affected by the inclusion of BMC. Conclusion. Our results indicated that the addition of BMC to scaffold is safe and has some potentially beneficial effects on osteochondral-tissue regeneration, but not on the functional endpoint of orthopaedic interest. Cite this article: Bone Joint Res 2021;10(10):677–689

The management of symptomatic osteochondral lesions of the talus (OLTs) can be challenging. The number of ways of treating these lesions has increased considerably during the last decade, with published studies often providing conflicting, low-level evidence. This paper aims to present an up-to-date concise overview of the best evidence for the surgical treatment of OLTs. Management options are reviewed based on the size of the lesion and include bone marrow stimulation, bone grafting options, drilling techniques, biological preparations, and resurfacing. Although many of these techniques have shown promising results, there remains little high level evidence, and further large scale prospective studies and systematic reviews will be required to identify the optimal form of treatment for these lesions.

Cite this article: Bone Joint J 2021;103-B(2):207–212.

Bone remodelling is mediated through the synchronism of bone resorption (catabolism) by osteoclasts and bone formation (anabolism) by osteoblasts. Imbalances in the bone remodelling cycle represent an underling cause of metabolic bone diseases such as osteoporosis, where bone resorption exceeds formation (1). Current therapeutic strategies to repair osteoporotic bone fractures focus solely in targeting anabolism or supressing catabolism (2). However, these therapeutics do not reverse the structural damage present at the defect site, ultimately leading to impaired fracture healing, making the repair of osteoporotic fractures particularly challenging in orthopaedics. Herein, we focus on investigating a combined versatile pro-anabolic and anti-catabolic effect of Magnesium (Mg. 2+. ) to modulate bone cell behaviour (3), to develop an engineered biomimetic bio-instructive biomaterial scaffold structurally designed to enhance bone formation while impeding pathological osteoclast resorption activities to facilitate better bone healing and promote repair. Pre-osteoblasts MC3T3-E1 (OBs) and osteoclasts progenitors RAW 264.7 (OCs) cell lines were cultured in growth media exposed to increasing concentrations of MgCl. 2. (0, 0.5, 1, 10, 25 and 50mM) and the optimal concentration to concurrently promote the differentiation of OBs and inhibit the differentiation or funtion of RANKL-induced OCs was assessed. We next used Fluorescence Lifetime Imaging Microscopy to investigate changes in the metabolic pathways during OBs and OCs differentiation when exposed to increasing MgCl. 2. concentrations. We developed a range of magnesium-incorporated collagen scaffolds to permit the spatiotemporal release of Mg. 2+. within the established therapeutic window, and to investigate the behaviour of bone cells in a 3D environment. In our results, we reported an increase in the expression of the bone formation markers osteocalcin and osteopontin for OBs exposed to 10mM MgCl. 2. , and a significant downregulation of the osteoclast-specific markers TRAP and cathepsin K in RANKL-induced OCs differentiation when exposed to 25mM MgCl. 2. Moreover, 25mM MgCl. 2. induced changes in the energy metabolism of OCs from a predominantly oxidative phosphorylation towards a more glycolytic pathway suggesting a regulatory effect of Mg. 2+. in the underlying mechanisms of osteoclasts formation and function. The developed porous collagen-magnesium scaffolds significantly reduced the expression of early osteoclastogenic markers RANK and NFkB, and an elevated expression of the osteogenic markers Runx2 and Col1A1 was reported after 7 days. Our research to date has provided evidences to demonstrate the potential of Mg. 2+. to concurrently enhance osteogenesis while inhibiting osteoclastogenesis in vitro, potentially introducing new targets for developing therapies to repair osteoporotic bone fractures

Aims

Bone demonstrates good healing capacity, with a variety of strategies being utilized to enhance this healing. One potential strategy that has been suggested is the use of stem cells to accelerate healing.

Adherent cells are known to respond to physical characteristics of their surrounding microenvironment, adapting their cytoskeleton and initiating signaling cascades specific to the type of cue encountered. Scaffolds mimicking native biophysical cues have proven to differentiate stem cells towards tissue-specific lineages and to maintain the phenotype of somatic cells for longer periods of culture time. Although the characteristic anisotropy of tendon tissue is commonly replicated in scaffolds, relevant physical cues such as tendon rigidity or mechanical loading are often neglected. The objective of this study is to use tendons' main extracellular matrix component, collagen type I, to create scaffolds with an anisotropic surface topography and controlled rigidity, in an effort to engineer functional tendon tissue equivalents, with native organization and strength.

Porcine collagen type I in solution was treated with one of the following cross-linkers: glutaraldehyde, genipin or 4-arm polyethylene glycol (4SP). The resulting mixture was poured on micro-grooved (2×2×2 μm) or planar polydimethylsiloxane (PDMS) molds and dried in a laminar flow hood to obtain 5 mg/ml collagen films. Surface topography and elastic modulus of the final scaffolds were analyzed using SEM/AFM and rheometry, respectively. Human tendon cells were isolated from adult tendon tissue and cultured on micro-grooved/planar scaffolds for 4, 7 and 10 days. Cell morphology, collagen III and tenascin C expression were analyzed by immunocytochemistry.

Among the different cross-linkers used, only the treatment with 4SP resulted in scaffolds with a recognizable micro-grooved surface topography. Precise control over the micro-grooved topography and the rigidity of the scaffolds was achieved by cross-linking the collagen with varying concentrations of 4SP at low pH and temperature. The elastic modulus of the scaffolds cross-linked with the highest concentration of 4SP matched the physiological values reported in developing tendons (∼15 kPa). Around eighty percent of the human tendon cells cultured on the cross-linked collagen films aligned in the direction of the anisotropy for 10 days in culture. At 4 days, tenoyctes cultured on micro-grooved substrates presented a significant higher nuclei aspect ratio than tenocytes cultured on planar substrates for all the 4SP concentrations. Synthesis, deposition and alignment of collagen III and tenascin C, two important tenogenic markers, were up regulated selectively in the rigid micro-grooved scaffolds after 7 days in culture. These results highlight the synergistic effect of matrix rigidity and cell alignment on tenogenic cell lineage commitment.

Collectively, this study provides new insights into how collagen can be modulated to create scaffolds with precise imprinted topographies and controlled rigidities. Gene expression analysis and a replicate study with hBMSCs will be carried out to support the first results and to further identify the optimal biophysical conditions for tenogenic cell lineage commitment. This potentially leads to the design of smart implants that not only restore immediate tendon functionality but also provide microscopic cues that drive cellular synthesis of organized tissue-specific matrix.

Objectives

Bone tissue engineering is one of the fastest growing branches in modern bioscience. New methods are being developed to achieve higher grades of mineral deposition by osteogenically inducted mesenchymal stem cells. In addition to well established monolayer cell culture models, 3D cell cultures for stem cell-based osteogenic differentiation have become increasingly attractive to promote in vivo bone formation. One of the main problems of scaffold-based osteogenic cell cultures is the difficulty in quantifying the amount of newly produced extracellular mineral deposition, as a marker for new bone formation, without destroying the scaffold. In recent studies, we were able to show that ^99mTc-methylene diphosphonate (^99mTc-MDP), a gamma radiation-emitting radionuclide, can successfully be applied as a reliable quantitative marker for mineral deposition as this tracer binds with high affinity to newly produced hydroxyapatite (HA).

Objectives

Meniscal injuries are often associated with an active lifestyle. The damage of meniscal tissue puts young patients at higher risk of undergoing meniscal surgery and, therefore, at higher risk of osteoarthritis. In this study, we undertook proof-of-concept research to develop a cellularized human meniscus by using 3D bioprinting technology.

Collagen scaffolds are generally characterized by their random fibre distribution and weak mechanical properties, which makes them unsuitable as substitutes for highly anisotropic tissues such as cornea or tendon. Recently, we developed a technique to create collagen type I scaffolds with well-defined anisotropic micro-patterns. Porcine collagen was mixed with PBS10X, NaOH and one of the following cross-linkers: glutaraldehyde (GTA), genipin and 4-arm polyethylene glycol (4SP). The resulting mixture was casted on micro-grooved (2×2×2 μm) polydimethylsiloxane (PDMS) moulds and allowed to dry in a laminar flow hood to obtain 5mg/ml collagen films. Different pH, temperatures (Tº), and cross-linker concentrations were tested in the process. Collagen gelation kinetics was analysed with rheometry and surface topography was assessed with scanning electron microscopy (SEM). Human bone marrow stem cells (HBMSCs) were seeded on the films and cell alignment was analysed by rhodamine/phalloidin staining and imaged with fluorescence microscopy. From all three cross-linkers tested, only 4SP cross-linked scaffolds showed a well-defined micro-grooved pattern. Increasing pH and Tº on 4SP-treated collagen decreased gelation time, which resulted in complete inhibition of the pattern, suggesting that an initial low viscous solution is required for a correct PDMS pattern infiltration. A wide range of 4SP concentrations (0.5, 1, 1.5 mM) maintained the well-defined topography on the films, opening the door to future fine-tuning of the stiffness sensed by cells. hBMSCs seeded on top of the scaffolds aligned along the pattern for 14 days in culture. Collectively, this data highlights the potential of these collagen scaffolds as tendon substitutes

Porcine and fish by-products in particular are rich sources for collagen, which is the main component of the extracellular matrix (ECM). Although there are studies investigating different collagen derived from various tissue sources for the purpose of creating biomaterials, the comparison of biophysical, biochemical and biological properties of type II collagen isolated from cartilaginous tissues has yet to be assessed. In addition, it has been shown from previous studies that sex steroid hormones affect the collagen content in male and female animals, herein, type II collagens from male and female porcine cartilage were assessed in order to investigate gender effects on the property of collagen scaffolds. Moreover, type II collagen has a supportive role in articular cartilage in the knee joint. Therefore, the aim is to assess the properties of type II collagen scaffolds as a function of species, tissue and gender for cartilage regeneration. Type II collagen was extracted from male and female porcine trachea, auricular, articular cartilage and cartilaginous fish through acid-pepsin digestion at 4°C. SDS-PAGE was conducted to confirm the purity of extracted collagen. Collagen sponges were created via freeze-drying. Scaffold structure and pore size were evaluated by scanning electron microscopy (SEM). Thermal stability was assessed by differential scanning calorimetry (DSC). Sponges were seeded with human adipose derived stem cells to assess chondro-inductive potential of collagen sponges after 7, 14 and 21 days of culture. In conclusion, collagen sponges support the proliferation and differentiation of human adipose derived stem cells to different extents