Femoroacetabular Impingement and the Effect of Osteochondroplasty on Hip Osteoarthritis Prevention: The Pandora's Box Opening Process.

OBJECTIVE: This study was conducted to assess the effect of osteochondroplasty on osteoarthritis (OA) prevention, comparing radiological evolution between identical hips from the same patient who had undergone unilateral surgery. DESIGN: We retrospectively reviewed radiological evolution between hips with similar shape from the same patient who had undergone unilateral surgery. In all, 56 FAI patients (112 hips) with a mean age of 42.18 ± 9.16 years and had undergone unilateral arthroscopy treatment have been included. Four independent researchers measured Wiberg, Acetabular and Alpha angles, Extrusion index, and Tönnis classification preoperatively to verify that operated and non-operated hips had the same shape. OA evolution was assessed by joint space width (JSW) in 3 different articular points and Tönnis classification. RESULTS: No preoperative anatomical differences were present between groups (P > 0.05). At the end of follow-up (31.9 months), a decrease of JSW in the 3 points measured was found in OP hips (OP vs. N-OP; P < 0.01). These results were correlated with changes in the proportion of patients who progressed to grade III in Tönnis classification (from 1.3% preoperative to 23.2% at the end of follow-up). CONCLUSIONS: Osteochondroplasty and labrum procedures were not associated with OA prevention. The OP hips showed a faster OA degeneration, which was not seen in the N-OP. These results will encourage hip surgeons to perform further investigations to avoid the "Pandora's Box Opening Process."

Silane-modified hydroxyapatite nanoparticles incorporated into polydioxanone/poly(lactide-co-caprolactone) creates a novel toughened nanocomposite with improved material properties and in vivo inflammatory responses.

The interface tissue between bone and soft tissues, such as tendon and ligament (TL), is highly prone to injury. Although different biomaterials have been developed for TL regeneration, few address the challenges of the TL-bone interface. Here, we aim to develop novel hybrid nanocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL), and hydroxyapatite (HA) nanoparticles suitable for TL-bone interface repair. Nanocomposites, containing 3-10% of both unmodified and chemically modified hydroxyapatite (mHA) with a silane coupling agent. We then explored biocompatibility through in vitro and in vivo studies using a subcutaneous mouse model. Through different characterisation tests, we found that mHA increases tensile properties, creates rougher surfaces, and reduces crystallinity and hydrophilicity. Morphological observations indicate that mHA nanoparticles are attracted by PDO rather than LCL phase, resulting in a higher degradation rate for mHA group. We found that adding the 5% of nanoparticles gives a balance between the properties. In vitro experiments show that osteoblasts' activities are more affected by increasing the nanoparticle content compared with fibroblasts. Animal studies indicate that both HA and mHA nanoparticles (10%) can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. In summary, this work highlights the potential of PDO/LCL/HA nanocomposites as an excellent biomaterial for TL-bone interface tissue engineering applications.

An engineered periosteum for efficient delivery of rhBMP-2 and mesenchymal progenitor cells during bone regeneration.

During bone regeneration, the periosteum acts as a carrier for key regenerative cues, delivering osteochondroprogenitor cells and crucial growth factors to the injured bone. We developed a biocompatible, 3D polycaprolactone (PCL) melt electro-written membrane to act as a mimetic periosteum. Poly (ethyl acrylate) coating of the PCL membrane allowed functionalization, mediated by fibronectin and low dose recombinant human BMP-2 (rhBMP-2) (10-25 µg/ml), resulting in efficient, sustained osteoinduction in vitro. In vivo, rhBMP-2 functionalized mimetic periosteum demonstrated regenerative potential in the treatment of rat critical-size femoral defects with highly efficient healing and functional recovery (80%-93%). Mimetic periosteum has also proven to be efficient for cell delivery, as observed through the migration of transplanted periosteum-derived mesenchymal cells to the bone defect and their survival. Ultimately, mimetic periosteum demonstrated its ability to deliver key stem cells and morphogens to an injured site, exposing a therapeutic and translational potential in vivo when combined with unprecedentedly low rhBMP-2 doses.

CC-Chemokine Receptor-2 Expression in Osteoblasts Contributes to Cartilage and Bone Damage during Post-Traumatic Osteoarthritis.

In osteoarthritis (OA), bone changes are radiological hallmarks and are considered important for disease progression. The C-C chemokine receptor-2 (CCR2) has been shown to play an important role in bone physiology. In this study, we investigated whether Ccr2 osteoblast-specific inactivation at different times during post-traumatic OA (PTOA) progression improves joint structures, bone parameters, and pain. We used a tamoxifen-inducible Ccr2 inactivation in Collagen1α-expressing cells to obtain osteoblasts lacking Ccr2 (CCR2-Col1αKO). We stimulated PTOA changes in CCR2-Col1αKO and CCR2+/+ mice using the destabilization of the meniscus model (DMM), inducing recombination before or after DMM (early- vs. late-inactivation). Joint damage was evaluated at two, four, eight, and twelve weeks post-DMM using multiple scores: articular-cartilage structure (ACS), Safranin-O, histomorphometry, osteophyte size/maturity, subchondral bone thickness and synovial hyperplasia. Spontaneous and evoked pain were assessed for up to 20 weeks. We found that early osteoblast-Ccr2 inactivation delayed articular cartilage damage and matrix degeneration compared to CCR2+/+, as well as DMM-induced bone thickness. Osteophyte formation and maturation were only minimally affected. Late Collagen1α-Ccr2 deletion led to less evident improvements. Osteoblast-Ccr2 deletion also improved static measures of pain, while evoked pain did not change. Our study demonstrates that Ccr2 expression in osteoblasts contributes to PTOA disease progression and pain by affecting both cartilage and bone tissues.

Novel hybrid biocomposites for tendon grafts: The addition of silk to polydioxanone and poly(lactide-co-caprolactone) enhances material properties, in vitro and in vivo biocompatibility.

Biopolymers play a critical role as scaffolds used in tendon and ligament (TL) regeneration. Although advanced biopolymer materials have been proposed with optimised mechanical properties, biocompatibility, degradation, and processability, it is still challenging to find the right balance between these properties. Here, we aim to develop novel hybrid biocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL) and silk to produce high-performance grafts suitable for TL tissue repair. Biocomposites containing 1-15% of silk were studied through a range of characterisation techniques. We then explored biocompatibility through in vitro and in vivo studies using a mouse model. We found that adding up to 5% silk increases the tensile properties, degradation rate and miscibility between PDO and LCL phases without agglomeration of silk inside the composites. Furthermore, addition of silk increases surface roughness and hydrophilicity. In vitro experiments show that the silk improved attachment of tendon-derived stem cells and proliferation over 72 h, while in vivo studies indicate that the silk can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. Finally, we selected a promising biocomposite and created a prototype TL graft based on extruded fibres. We found that the tensile properties of both individual fibres and braided grafts could be suitable for anterior cruciate ligament (ACL) repair applications.

Sustained inhibition of CC-chemokine receptor-2 via intraarticular deposition of polymeric microplates in post-traumatic osteoarthritis.

Posttraumatic osteoarthritis (PTOA) is mostly treated via corticosteroid administration, and total joint arthroplasty continues to be the sole effective intervention in severe conditions. To assess the therapeutic potential of CCR2 targeting in PTOA, we used biodegradable microplates (µPLs) to achieve a slow and sustained intraarticular release of the CCR2 inhibitor RS504393 into injured knees and followed joint damage during disease progression. RS504393-loaded µPLs (RS-µPLs) were fabricated via a template-replica molding technique. A mixture of poly(lactic-co-glycolic acid) (PLGA) and RS504393 was deposited into 20 × 10 µm (length × height) wells in a polyvinyl alcohol (PVA) square-patterned template. After physicochemical and toxicological characterizations, the RS504393 release profile from µPL was assessed in PBS buffer. C57BL/6 J male mice were subjected to destabilization of the medial meniscus (DMM)/sham surgery, and RS-µPLs (1 mg/kg) were administered intraarticularly 1 week postsurgery. Administrations were repeated at 4 and 7 weeks post-DMM. Drug free-µPLs (DF-µPLs) and saline injections were performed as controls. Mice were euthanized at 4 and 10 weeks post-DMM, corresponding to the early and severe PTOA stages, respectively. Knees were evaluated for cartilage structure score (ACS, H&E), matrix loss (safranin O score), osteophyte formation and maturation from cartilage to bone (cartilage quantification), and subchondral plate thickness. The RS-µPL architecture ensured the sustained release of CCR2 inhibitors over several weeks, with ~ 20% of RS504393 still available at 21 days. This prolonged release improved cartilage structure and reduced bone damage and synovial hyperplasia at both PTOA stages. Extracellular matrix loss was also attenuated, although with less efficacy. The results indicate that local sustained delivery is needed to optimize CCR2-targeted therapies.

3D printed bioresorbable scaffolds for articular cartilage tissue engineering: a comparative study between neat polycaprolactone (PCL) and poly(lactide-b-ethylene glycol) (PLA-PEG) block copolymer.

This work identifies and describes different material-scaffold geometry combinations for cartilage tissue engineering (CTE). Previously reported potentially interesting scaffold geometries were tuned and printed using bioresorbable polycaprolactone and poly(lactide-b-ethylene) block copolymer. Medical grades of both polymers were 3D printed with fused filament fabrication technology within an ISO 7 classified cleanroom. Resulting scaffolds were then optically, mechanically and biologically tested. Results indicated that a few material-scaffold geometry combinations present potential for excellent cell viability as well as for an enhance of the chondrogenic properties of the cells, hence suggesting their suitability for CTE applications.

The bone marrow niche regulates redox and energy balance in MLL::AF9 leukemia stem cells.

Eradicating leukemia requires a deep understanding of the interaction between leukemic cells and their protective microenvironment. The CXCL12/CXCR4 axis has been postulated as a critical pathway dictating leukemia stem cell (LSC) chemoresistance in AML due to its role in controlling cellular egress from the marrow. Nevertheless, the cellular source of CXCL12 in the acute myeloid leukemia (AML) microenvironment and the mechanism by which CXCL12 exerts its protective role in vivo remain unresolved. Here, we show that CXCL12 produced by Prx1+ mesenchymal cells but not by mature osteolineage cells provide the necessary cues for the maintenance of LSCs in the marrow of an MLL::AF9-induced AML model. Prx1+ cells promote survival of LSCs by modulating energy metabolism and the REDOX balance in LSCs. Deletion of Cxcl12 leads to the accumulation of reactive oxygen species and DNA damage in LSCs, impairing their ability to perpetuate leukemia in transplantation experiments, a defect that can be attenuated by antioxidant therapy. Importantly, our data suggest that this phenomenon appears to be conserved in human patients. Hence, we have identified Prx1+ mesenchymal cells as an integral part of the complex niche-AML metabolic intertwining, pointing towards CXCL12/CXCR4 as a target to eradicate parenchymal LSCs in AML.

Molecular and Cellular Mechanisms of Delayed Fracture Healing in Mmp10 (Stromelysin 2) Knockout Mice.

The remodeling of the extracellular matrix is a central function in endochondral ossification and bone homeostasis. During secondary fracture healing, vascular invasion and bone growth requires the removal of the cartilage intermediate and the coordinate action of the collagenase matrix metalloproteinase (MMP)-13, produced by hypertrophic chondrocytes, and the gelatinase MMP-9, produced by cells of hematopoietic lineage. Interfering with these MMP activities results in impaired fracture healing characterized by cartilage accumulation and delayed vascularization. MMP-10, Stromelysin 2, a matrix metalloproteinase with high homology to MMP-3 (Stromelysin 1), presents a wide range of putative substrates identified in vitro, but its targets and functions in vivo and especially during fracture healing and bone homeostasis are not well defined. Here, we investigated the role of MMP-10 through bone regeneration in C57BL/6 mice. During secondary fracture healing, MMP-10 is expressed by hematopoietic cells and its maximum expression peak is associated with cartilage resorption at 14 days post fracture (dpf). In accordance with this expression pattern, when Mmp10 is globally silenced, we observed an impaired fracture-healing phenotype at 14 dpf, characterized by delayed cartilage resorption and TRAP-positive cell accumulation. This phenotype can be rescued by a non-competitive transplant of wild-type bone marrow, indicating that MMP-10 functions are required only in cells of hematopoietic linage. In addition, we found that this phenotype is a consequence of reduced gelatinase activity and the lack of proMMP-9 processing in macrophages. Our data provide evidence of the in vivo function of MMP-10 during endochondral ossification and defines the macrophages as the lead cell population in cartilage removal and vascular invasion. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Phase II multicenter randomized controlled clinical trial on the efficacy of intra-articular injection of autologous bone marrow mesenchymal stem cells with platelet rich plasma for the treatment of knee osteoarthritis.

BACKGROUND: Mesenchymal stromal cells are a safe and promising option to treat knee osteoarthritis as previously demonstrated in different clinical trials. However, their efficacy, optimal dose and addition of adjuvants must be determined. Here, we evaluated the clinical effects of a dose of 100 × 106 bone marrow mesenchymal stromal cells (BM-MSCs) in combination with Platelet Rich Plasma (PRGF®) as adjuvant in a randomized clinical trial. METHODS: A phase II, multicenter, randomized clinical trial with active control was conducted. Sixty patients diagnosed with knee OA were randomly assigned to 3 weekly doses of PRGF® or intraarticular administration of 100 × 106 cultured autologous BM-MSCs plus PRGF®. Patients were followed up for 12 months, and pain and function were assessed using VAS and WOMAC and by measuring the knee range of motion range. X-ray and magnetic resonance imaging analyses were performed to analyze joint damage. RESULTS: No adverse effects were reported after BM-MSC administration or during follow-up. According to VAS, the mean value (SD) for PRGF® and BM-MSC with PRGF® went from 5 (1.8) to 4.5 (2.2) (p = 0.389) and from 5.3 (1.9) to 3.5 (2.5) (p = 0.01), respectively at 12 months. In WOMAC, the mean (SD) baseline and 12-month overall WOMAC scores in patients treated with PRGF® was 31.9 (16.2) and 22.3 (15.8) respectively (p = 0.002) while that for patients treated with BM-MSC plus PRGF® was 33.4 (18.7) and 23.0 (16.6) (p = 0.053). Although statistical significances between groups have been not detected, only patients being treated with BM-MSC plus PRGF® could be considered as a OA treatment responders following OARSI criteria. X-ray and MRI (WORMS protocol) revealed no changes in knee joint space width or joint damage. CONCLUSIONS: Treatment with BM-MSC associated with PRGF® was shown to be a viable therapeutic option for osteoarthritis of the knee, with clinical improvement at the end of follow-up. Further phase III clinical trials would be necessary to confirm the efficacy. Trial registration Clinical Trials.gov identifier NCT02365142. Nº EudraCT: 2011-006036-23.

Engineering a Humanised Niche to Support Human Haematopoiesis in Mice: Novel Opportunities in Modelling Cancer.

Despite the bone marrow microenvironment being widely recognised as a key player in cancer research, the current animal models that represent a human haematopoietic system lack the contribution of the humanised marrow microenvironment. Here we describe a murine model that relies on the combination of an orthotopic humanised tissue-engineered bone construct (ohTEBC) with patient-specific bone marrow (BM) cells to create a humanised bone marrow (hBM) niche capable of supporting the engraftment of human haematopoietic cells. Results showed that this model supports the engraftment of human CD34+ cells from a healthy BM with human haematopoietic cells migrating into the mouse BM, human BM compartment, spleen and peripheral blood. We compared these results with the engraftment capacity of human CD34+ cells obtained from patients with multiple myeloma (MM). We demonstrated that CD34+ cells derived from a diseased BM had a reduced engraftment potential compared to healthy patients and that a higher cell dose is required to achieve engraftment of human haematopoietic cells in peripheral blood. Finally, we observed that hematopoietic cells obtained from the mobilised peripheral blood of patients yields a higher number of CD34+, overcoming this problem. In conclusion, this humanised mouse model has potential as a unique and patient-specific pre-clinical platform for the study of tumour-microenvironment interactions, including human bone and haematopoietic cells, and could, in the future, serve as a drug testing platform.

Anisotropic Cryostructured Collagen Scaffolds for Efficient Delivery of RhBMP-2 and Enhanced Bone Regeneration.

In the treatment of bone non-unions, an alternative to bone autografts is the use of bone morphogenetic proteins (BMPs), e.g., BMP-2, BMP-7, with powerful osteoinductive and osteogenic properties. In clinical settings, these osteogenic factors are applied using absorbable collagen sponges for local controlled delivery. Major side effects of this strategy are derived from the supraphysiological doses of BMPs needed, which may induce ectopic bone formation, chronic inflammation, and excessive bone resorption. In order to increase the efficiency of the delivered BMPs, we designed cryostructured collagen scaffolds functionalized with hydroxyapatite, mimicking the structure of cortical bone (aligned porosity, anisotropic) or trabecular bone (random distributed porosity, isotropic). We hypothesize that an anisotropic structure would enhance the osteoconductive properties of the scaffolds by increasing the regenerative performance of the provided rhBMP-2. In vitro, both scaffolds presented similar mechanical properties, rhBMP-2 retention and delivery capacity, as well as scaffold degradation time. In vivo, anisotropic scaffolds demonstrated better bone regeneration capabilities in a rat femoral critical-size defect model by increasing the defect bridging. In conclusion, anisotropic cryostructured collagen scaffolds improve bone regeneration by increasing the efficiency of rhBMP-2 mediated bone healing.

Periosteum-derived mesenchymal progenitor cells in engineered implants promote fracture healing in a critical-size defect rat model.

An attractive alternative to bone autografts is the use of autologous mesenchymal progenitor cells (MSCs) in combination with biomaterials. We compared the therapeutic potential of different sources of mesenchymal stem cells in combination with biomaterials in a bone nonunion model. A critical-size defect was created in Sprague-Dawley rats. Animals were divided into six groups, depending on the treatment to be applied: bone defect was left empty (CTL); treated with live bone allograft (LBA); hrBMP-2 in collagen scaffold (CSBMP2 ); acellular polycaprolactone scaffold (PCL group); PCL scaffold containing periosteum-derived MSCs (PCLPMSCs ) and PCL containing bone marrow-derived MSCs (PCLBMSCs ). To facilitate cell tracking, both MSCs and bone graft were isolated from green fluorescent protein (GFP)-transgenic rats. CTL group did not show any signs of healing during the radiological follow-up (n = 6). In the LBA group, all the animals showed bone bridging (n = 6) whereas in the CSBMP2 group, four out of six animals demonstrated healing. In PCL and PCLPMSCs groups, a reduced number of animals showed radiological healing, whereas no healing was detected in the PCLBMSCs group. Using microcomputed tomography, the bone volume filling the defect was quantified, showing significant new bone formation in the LBA, CSBMP2 , and PCLPMSCs groups when compared with the CTL group. At 10 weeks, GFP positive cells were detected only in the LBA group and restricted to the outer cortical bone in close contact with the periosteum. Tracking of cellular implants demonstrated significant survival of the PMSCs when compared with BMSCs. In conclusion, PMSCs improve bone regeneration being suitable for mimetic autograft design.

Effect of bone marrow stromal cells in combination with biomaterials in early phases of distraction osteogenesis: An experimental study in a rabbit femur model.

Acceleration of the consolidation of the distracted bone is a relevant medical need. As a platform to improve in vivo bone engineering, we developed a novel distraction osteogenesis (DO) model in a rabbit large bone (femur) and tested if the application of cultured bone marrow stromal cells (BMSCs) immediately after the osteotomy promotes the formation of bone. This report consists of two components, an animal study to evaluate the quality of the regenerate following different treatments and an in vitro study to evaluate osteogenic potential of BMSC cultures. To illuminate the mechanism of action of injected cells, we tested stem cell cultures enriched in osteogenic-BMSCs (O-BMSCs) as compared with cultures enriched in non-osteogenic BMSCs (NO-BMSCs). Finally, we included a group of animals treated with biomaterials (fibrin and ground cortical bone) in addition to cells. Injection of O-BMSCs promoted the maturity of distracted callus and decreased fibrosis. When combined with biomaterials, O-BMSCs modified the ossification pattern from endochondral to intramembranous type. The use of NO-BMSCs not only did not increase the maturity but also increased porosity of the bone. These preclinical results indicate that the BMSC cultures must be tested in vitro prior to clinical use, since a number of factors may influence their outcome in bone formation. We hypothesize that the use of osteogenic BMSCs and biomaterials could be clinically beneficial to shorten the consolidation period of the distraction and the total period of bone lengthening.

Intra-articular injection of two different doses of autologous bone marrow mesenchymal stem cells versus hyaluronic acid in the treatment of knee osteoarthritis: long-term follow up of a multicenter randomized controlled clinical trial (phase I/II).

BACKGROUND: Mesenchymal stromal cells (MSCs) are a promising option to treat knee osteoarthritis (OA). Their safety and usefulness have been reported in several short-term clinical trials but less information is available on the long-term effects of MSC in patients with osteoarthritis. We have evaluated patients included in our previous randomized clinical trial (CMM-ART, NCT02123368) to determine their long-term clinical effect. MATERIALS: A phase I/II multicenter randomized clinical trial with active control was conducted between 2012 and 2014. Thirty patients diagnosed with knee OA were randomly assigned to Control group, intraarticularly administered hyaluronic acid alone, or to two treatment groups, hyaluronic acid together with 10 × 106 or 100 × 106 cultured autologous bone marrow-derived MSCs (BM-MSCs), and followed up for 12 months. After a follow up of 4 years adverse effects and clinical evolution, assessed using VAS and WOMAC scorings are reported. RESULTS: No adverse effects were reported after BM-MSCs administration or during the follow-up. BM-MSCs-administered patients improved according to VAS, median value (IQR) for Control, Low-dose and High-dose groups changed from 5 (3, 7), 7 (5, 8) and 6 (4, 8) to 7 (6, 7), 2 (2, 5) and 3 (3, 4), respectively at the end of follow up (Low-dose vs Control group, p = 0.01; High-dose vs Control group, p = 0.004). Patients receiving BM-MSCs also improved clinically according to WOMAC. Control group showed an increase median value of 4 points (- 11;10) while Low-dose and High-dose groups exhibited values of - 18 (- 28;- 9) and - 10 (- 21;- 3) points, respectively (Low-dose vs Control group p = 0.043). No clinical differences between the BM-MSCs receiving groups were found. CONCLUSIONS: Single intraarticular injection of in vitro expanded autologous BM-MSCs is a safe and feasible procedure that results in long-term clinical and functional improvement of knee OA.

Tissue Mimicry in Morphology and Composition Promotes Hierarchical Matrix Remodeling of Invading Stem Cells in Osteochondral and Meniscus Scaffolds.

An integral approach toward in situ tissue engineering through scaffolds that mimic tissue with regard to both tissue architecture and biochemical composition is presented. Monolithic osteochondral and meniscus scaffolds are prepared with tissue analog layered biochemical composition and perpendicularly oriented continuous micropores by a newly developed cryostructuring technology. These scaffolds enable rapid cell ingrowth and induce zonal-specific matrix synthesis of human multipotent mesenchymal stromal cells solely through their design without the need for supplementation of soluble factors such as growth factors.

Mechanical barriers and transforming growth factor beta inhibitor on epidural fibrosis in a rabbit laminectomy model.

BACKGROUND: TGF-ß has been described as a mediator of fibrosis and scarring. Several studies achieved reduction in experimental scarring through the inhibition of TGF-ß. Fibroblasts have been defined as the cell population originating fibrosis, blocking fibroblast invasion may impair epidural fibrosis appearance. For this purpose, biocompatible materials used as mechanical barriers and a TGF-ß inhibitor peptide were evaluated in the reduction of epidural fibrosis. METHODS: A L6 laminectomy was performed in 40 New Zealand white rabbits. Divided into four groups, each rabbit was assigned to receive either collagen sponge scaffold (CS group), gelatin-based gel (GCP group), P144® (iTGFß group), or left untreated (control group). Four weeks after surgery, cell density, collagen content, and new bone formation of the scar area were determined by histomorphometry. Two experienced pathologists scored dura mater adhesion, scar density, and inflammatory infiltrate in a blinded manner. RESULTS: In all groups, laminectomy site was filled with fibrous tissue and the dura mater presented adhesions. Only GCP group presented a significant reduction in collagen content and scar density. CONCLUSION: GCP treatment reduces epidural fibrosis although did not prevent dura mater adhesion completely.

Autologous bioscaffolds based on different concentrations of platelet rich plasma and synovial fluid as a vehicle for mesenchymal stem cells.

In the field of tissue engineering, diverse types of bioscaffolds are being developed currently for osteochondral defect applications. In this work, a novel scaffold based on platelet rich plasma (PRP) and hyaluronic acid with mesenchymal stem cells (MSCs) has been evaluated to observe its effect on immobilized cells. The bioscaffolds were prepared by mixing different volumes of synovial fluid (SF) with PRP from patients obtaining three formulations at PRP-SF ratios of 3:1, 1:1 and 1:3 (v/v). The live/dead staining revealed that although the cell number of each type of bioscaffold was different, these this constructs provide cells with a suitable environment for their viability and proliferation. Moreover, immobilized MSCs showed their ability to secrete fibrinolytic enzymes, which vary depending on the fibrin amount of the scaffold. Immunohistochemical analysis revealed the positive staining for collagen type II in all cases, proving the biologic action of SF derived MSCs together with the suitable characteristics of the bioscaffold for chondrogenic differentiation. Considering all these aspects, this study demonstrates that these cells-based constructs represent an attractive method for cell immobilization, achieving completely autologous and biocompatible scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 377-385, 2018.

Modulation of Synovial Fluid-Derived Mesenchymal Stem Cells by Intra-Articular and Intraosseous Platelet Rich Plasma Administration.

The aim of this study was to evaluate the effect of intra-articular (IA) or a combination of intra-articular and intraosseous (IO) infiltration of Platelet Rich Plasma (PRP) on the cellular content of synovial fluid (SF) of osteoarthritic patients. Thirty-one patients received a single infiltration of PRP either in the IA space (n = 14) or in the IA space together with two IO infiltrations, one in the medial femoral condyle and one in the tibial plateau (n = 17). SF was collected before and after one week of the infiltration. The presence in the SF of mesenchymal stem cells (MSCs), monocytes, and lymphocytes was determined and quantified by flow cytometry. The number and identity of the MSCs were further confirmed by colony-forming and differentiation assays. PRP infiltration into the subchondral bone (SB) and the IA space induced a reduction in the population of MSCs in the SF. This reduction in MSCs was further confirmed by colony-forming (CFU-F) assay. On the contrary, IA infiltration alone did not cause variations in any of the cellular populations by flow cytometry or CFU-F assay. The SF of osteoarthritic patients contains a population of MSCs that can be modulated by PRP infiltration of the SB compartment.

Intra-articular injection of two different doses of autologous bone marrow mesenchymal stem cells versus hyaluronic acid in the treatment of knee osteoarthritis: multicenter randomized controlled clinical trial (phase I/II).

BACKGROUND: Mesenchymal stromal cells are a promising option to treat knee osteoarthritis. Their safety and usefulness must be confirmed and the optimal dose established. We tested increasing doses of bone marrow mesenchymal stromal cells (BM-MSCs) in combination with hyaluronic acid in a randomized clinical trial. MATERIALS: A phase I/II multicenter randomized clinical trial with active control was conducted. Thirty patients diagnosed with knee OA were randomly assigned to intraarticularly administered hyaluronic acid alone (control), or together with 10 × 10(6) or 100 × 10(6) cultured autologous BM-MSCs, and followed up for 12 months. Pain and function were assessed using VAS and WOMAC and by measuring the knee motion range. X-ray and magnetic resonance imaging analyses were performed to analyze joint damage. RESULTS: No adverse effects were reported after BM-MSC administration or during follow-up. BM-MSC-administered patients improved according to VAS during all follow-up evaluations and median value (IQR) for control, low-dose and high-dose groups change from 5 (3, 7), 7 (5, 8) and 6 (4, 8) to 4 (3, 5), 2 (1, 3) and 2 (0,4) respectively at 12 months (low-dose vs control group p = 0.005 and high-dose vs control group p < 0.009). BM-MSC-administered patients were also superior according to WOMAC, although improvement in control and low-dose patients could not be significantly sustained beyond 6 months. On the other hand, the BM-MSC high-dose group exhibited an improvement of 16.5 (12, 19) points at 12 months (p < 0.01). Consistent with WOMAC and VAS values, motion ranges remained unaltered in the control group but improved at 12 months with BM-MSCs. X-ray revealed a reduction of the knee joint space width in the control group that was not seen in BM-MSCs high-dose group. MRI (WORMS protocol) showed that joint damage decreased only in the BM-MSC high-dose group, albeit slightly. CONCLUSIONS: The single intraarticular injection of in vitro expanded autologous BM-MSCs together with HA is a safe and feasible procedure that results in a clinical and functional improvement of knee OA, especially when 100 × 10(6) cells are administered. These results pave the way for a future phase III clinical trial. CLINICAL TRIALS: gov identifier NCT02123368. Nº EudraCT: 2009-017624-72.