Micro-fragmentation is a valid alternative to cell expansion and enzymatic digestion of adipose tissue for the treatment of knee osteoarthritis: a comparative preclinical study.

PURPOSE: The aim of this study was to compare three procedures to exploit adipose-derived cells for the treatment of osteoarthritis (OA) in a preclinical model, to understand their therapeutic potential and identify the most suitable approach for the clinical application. METHODS: Biological samples from adipose tissue, processed by mechanical micro-fragmentation (MF), enzymatic digestion (SVF) or cell expansion (ADSCs), were first characterized in vitro and then used in vivo in a surgically induced OA rabbit model: Group 1-control group (untreated 12 knees/saline 12 knees), Group 2-MF (24 knees), Group 3-SVF (24 knees), Group 4-ADSCs (24 knees). Macroscopic, histological, histomorphometric, immunohistochemical and blood and synovial fluid analyses were evaluated at 2 and 4 months from the treatments. RESULTS: Samples obtained by the three procedures yielded 85-95% of viable cells. In vivo assessments showed no significant side effects or inflammatory responses after the injection. The macroscopic Hanashi score did not show significant differences among treated groups and controls. The histopathological evaluation of synovial tissues showed lower signs of synovitis for MF, although the semiquantitative analysis (Krenn score) did not reach statistical significance. Instead, MF showed the best results both in terms of qualitative and semi-quantitative evaluations of articular cartilage, with a more uniform staining, a smoother surface and a significantly better Laverty score (p = 0.004). CONCLUSION: MF, SVF, and expanded ADSCs did not elicit significant local or systemic adverse reactions in this preclinical OA model. Among the different methods used to exploit the adipose tissue potential, MF showed the most promising findings in particular in terms of protection of the articular surface from the joint degenerative OA processes. LEVEL OF EVIDENCE: Preclinical animal study.

Release kinetic of pro- and anti-inflammatory biomolecules from platelet-rich plasma and functional study on osteoarthritis synovial fibroblasts.

BACKGROUND AIMS: This study evaluated the release kinetics of numerous representative and less studied platelet-rich plasma (PRP) cytokines/chemokines with regard to the effects of various cellular compositions and incubation times. In addition, the biological effects of different PRPs on osteoarthritis synovial fibroblasts in vitro were tested. METHODS: Peripheral whole blood was collected from healthy donors, and pure platelet-rich plasma (P-PRP), leukocyte-rich platelet-rich plasma (L-PRP) and platelet-poor plasma (PPP) were prepared for the analysis of the following biomolecules: IL-1ß, IL-4, IL-6, IL-10, IL-17a, IL-22, MIP-1α/CCL-3, RANTES/CCL-5, MCP-3/CCL-7, Gro-α/CXCL-1, PF-4/CXCL-4, ENA-78/CXCL-5, NAP-2/CXCL-7, IL-8/CXCL-8, Fractalkine/CX3CL-1, s-CD40L P-PRP, L-PRP and PPP. Their effect on osteoarthritis synovial fibroblasts in vitro was tested by analyzing changes induced in both gene expression on a panel of representative molecules involved in physiopathology of joint environment and synthesis of IL-1ß, IL-8 and hyaluronic acid. RESULTS: This study demonstrated that among the 16 analyzed biomolecules, four were undetectable, whereas most of the detected biomolecules were more concentrated in L-PRP even when concentrations were normalized to platelet number. Despite the pro-inflammatory boost, the various PRP preparations did not alter synovial fibroblast gene expression of specific factors that play a pivotal role in joint tissue homeostasis and are able to induce anti-inflammatory (TIMP-1) biomolecules. DISCUSSION: This study provides a set of reference data on the concentration and release kinetics of some less explored biomolecules that could represent potential specific effectors in the modulation of inflammatory processes and in tissue repair after treatment with PRP.

Long-term Results of Matrix-assisted Autologous Chondrocyte Transplantation Combined With Autologous Bone Grafting for the Treatment of Juvenile Osteochondritis Dissecans.

BACKGROUND: Osteochondritis dissecans is a pathology affecting young patients that involves the entire osteochondral unit. In the case of unfixable fragments, regenerative cartilage treatments are a viable solution, but little is known about the use of these procedures for the treatment of juvenile osteochondritis dissecans (JOCD). The aim of this study was to evaluate the long-term results offered by matrix-assisted autologous chondrocyte transplantation combined with autologous bone grafting for the treatment of JOCD. METHODS: Nineteen patients have been enrolled. The mean age at the time of treatment was 16.8±1.5 years, with a mean body mass index of 22.9±2.7. The average size of the defects was 2.8±1.2 cm. All patients were evaluated prospectively before surgery and at 12, 24, 60, and at a final follow-up of 120 months with International Knee Documentation Committee scores, EuroQol-Visual Analogue Scale, and the Tegner Score. RESULTS: A statistically significant improvement in all clinical scores was observed from baseline evaluation to 120 months of final follow-up. In particular, the International Knee Documentation Committee subjective score improved from the preoperative evaluation of 38.7±17.3 to 74.0±21.8 at 12 months (P<0.0005), with scores remaining stable for up to 120 months (83.8±20.7), with all follow-ups showing a statistically significant improvement compared with the basal value (P<0.0005). Three patients failed at 12 months, for a failure rate of 16% at 10 years of follow-up. Lesions >3.5 cm obtained worse subjective results. In addition, lesion size and female sex were significantly associated with failures. CONCLUSIONS: The matrix-assisted autologous chondrocyte transplantation technique with autologous bone grafting is a valid treatment option for JOCD in case of unfixable fragments. The clinical improvement obtained is significant and stable, with good results maintained for up to 10 years of follow-up and an overall low failure rate. Lesion size and sex could influence the clinical outcome and should be considered in the treatment choice. LEVEL OF EVIDENCE: Level IV-case series.

A Composite Chitosan-Reinforced Scaffold Fails to Provide Osteochondral Regeneration.

Several biomaterials have recently been developed to address the challenge of osteochondral regeneration. Among these, chitosan holds promises both for cartilage and bone healing. The aim of this in vivo study was to evaluate the regeneration potential of a novel hybrid magnesium-doped hydroxyapatite (MgHA), collagen, chitosan-based scaffold, which was tested in a sheep model to ascertain its osteochondral regenerative potential, and in a rabbit model to further evaluate its ability to regenerate bone tissue. Macroscopic, microtomography, histology, histomorphometry, and immunohistochemical analysis were performed. In the sheep model, all analyses did not show significant differences compared to untreated defects (p > 0.05), with no evidence of cartilage and subchondral bone regeneration. In the rabbit model, this bone scaffold provided less ability to enhance tissue healing compared with a commercial bone scaffold. Moreover, persistence of scaffold material and absence of integration with connective tissue around the scaffolds were observed. These results raised some concerns about the osteochondral use of this chitosan composite scaffold, especially for the bone layer. Further studies are needed to explore the best formulation of chitosan-reinforced composites for osteochondral treatment.

Regenerative Features of Adipose Tissue for Osteoarthritis Treatment in a Rabbit Model: Enzymatic Digestion Versus Mechanical Disruption.

Evaluating cell migration after cell-based treatment is important for several disorders, including osteoarthritis (OA), as it might influence the clinical outcome. This research explores migrating expanded-adipose stromal cells (ASCs) and adipose niches after enzymatic and mechanical processes. Bilateral anterior cruciate ligament transection induced a mild grade of OA at eight weeks in adult male New Zealand rabbits. ASCs, enzymatic stromal vascular fraction (SVF), and micro fragmented adipose tissue (MFAT) were intra-articularly injected in the knee joint. Assessments of cell viability and expression of specific markers, including CD-163 wound-healing macrophages, were done. Cell migration was explored through labelling with PKH26 dye at 7 and 30 days alongside co-localization analyses for CD-146. All cells showed good viability and high percentages of CD-90 and CD-146. CD-163 was significantly higher in MFAT compared to SVF. Distinct migratory potential and time-dependent effects were observed among cell-based treatments. At day 7, both ASCs and SVF migrated towards synovium, whereas for MFAT versus cartilage, a different migration pattern was noticed at day 30. The long-term distinct cell migration of ASCs, SVF, and MFAT open interesting clinical insights on their potential use for OA treatment. Moreover, the highest expression of CD-163 in MFAT, rather than SVF, might have an important role in directly mediating cartilage tissue repair responses.

Novel alginate biphasic scaffold for osteochondral regeneration: an in vivo evaluation in rabbit and sheep models.

Current therapeutic strategies for osteochondral restoration showed a limited regenerative potential. In fact, to promote the growth of articular cartilage and subchondral bone is a real challenge, due to the different functional and anatomical properties. To this purpose, alginate is a promising biomaterial for a scaffold-based approach, claiming optimal biocompatibility and good chondrogenic potential. A previously developed mineralized alginate scaffold was investigated in terms of the ability to support osteochondral regeneration both in a large and medium size animal model. The results were evaluated macroscopically and by microtomography, histology, histomorphometry, and immunohistochemical analysis. No evidence of adverse or inflammatory reactions was observed in both models, but limited subchondral bone formation was present, together with a slow scaffold resorption time.The implantation of this biphasic alginate scaffold provided partial osteochondral regeneration in the animal model. Further studies are needed to evaluate possible improvement in terms of osteochondral tissue regeneration for this biomaterial.

Injectable Systems for Intra-Articular Delivery of Mesenchymal Stromal Cells for Cartilage Treatment: A Systematic Review of Preclinical and Clinical Evidence.

Stem cell-based therapy is a promising approach to treat cartilage lesions and clinical benefits have been reported in a number of studies. However, the efficacy of cell injection procedures may be impaired by cell manipulation and damage as well as by cell dissemination to non-target tissues. To overcome such issues, mesenchymal stromal cell (MSC) delivery may be performed using injectable vehicles as containment systems that further provide a favorable cell microenvironment. The aim of this systematic review was to analyze the preclinical and clinical literature on platelet-rich plasma (PRP), hyaluronic acid (HA), and hydrogels for the delivery of MSCs. The systematic literature search was performed using the PubMed and Web of science databases with the following string: "(stem cells injection) AND (platelet rich plasma OR PRP OR platelet concentrate OR biomaterials OR hyaluronic acid OR hydrogels)": 40 studies (19 preclinical and 21 clinical) met the inclusion criteria. This review revealed an increasing interest on the use of injectable agents for MSC delivery. However, while negligible adverse events and promising clinical outcomes were generally reported, the prevalence of low quality studies hinders the possibility to demonstrate the real benefits of using such injectable systems. Specific studies must be designed to clearly demonstrate the added benefits of these systems to deliver MSCs for the treatment of cartilage lesions and osteoarthritis.

"Bone Morphogenic Protein augmentation for long bone healing" response to "Clinical need for bone morphogenetic protein".

We take advantage of the comments of Dr. Vukicevic et al. to clarify that the study focus did not include other diseases and locations than long bones; in this light, the articles that Dr. Vukicevic mentioned could not be selected. We would like to recognize the key contribution of Urist and the nice tribute of the International Orthopaedics heritage section on the BMPs discovery. While we could not refer to the latter, published after our search, we put emphasis on the steps of important discoveries that made BMPs available for clinical use, a road that started in 1965, when Urist showed that new bone formation could be induced by demineralized bone matrix, later identified as BMPs, and purified in the next three decades. In the past years, BMPs have been studied in several pre-clinical models. As this was not the focus of this systematic clinical review, only some pre-clinical papers were cited, aiming at underlining important aspects, such as the relationship between dosage and bone formation and the delivery material, which could influence BMPs release and effect, key factors requiring further studies to optimize BMPs augmentation, as mentioned in the discussion. While our article does not present the methodological strength of a meta-analysis, and while it was not possible to summarize the entire extensive literature on BMPs, we hope that our review could be useful to summarize the available evidence in terms of both BMPs augmentation potential and complications for the treatment of long bones affected by fractures, non-union, and osteonecrosis.

Clinical application of bone morphogenetic proteins for bone healing: a systematic review.

PURPOSE: This paper documents the existing evidence on bone morphogenetic proteins (BMPs) use for the treatment of bone fractures, non-union, and osteonecrosis, through a review of the clinical literature, underlying potential and limitations in terms of cost effectiveness and risk of complications. METHODS: A systematic review was performed on the PubMed database using the following string: (bone morphogenetic proteins OR BMPs) and (bone repair OR bone regeneration) including papers from 2000 to 2016. The search focused on clinical trials dealing with BMPs application to favor bone regeneration in bone fractures, non-union, and osteonecrosis, in English language, with level of evidence I, II, III, and IV. Relevant data (type of study, number of patients, BMPs delivery material, dose, site, follow-up, outcome, and adverse events) were extracted and analyzed. RESULTS: Forty-four articles met the inclusion criteria: 10 randomized controlled trials (RCTs), 7 comparative studies, 18 case series, and 9 case reports. rhBMP-2 was documented mainly for the treatment of fractures, and rhBMP-7 mainly for non-unions and osteonecrosis. Mixed results were found among RCTs and comparative papers: 11 reported positive results for BMPs augmentation, 3 obtained no significant effects, and 2 showed negative results. The only study comparing the two BMPs showed a better outcome with rhBMP-2 for non-union treatment. CONCLUSION: Clinical evidence on BMPs use for the treatment of fractures, non-union, and osteonecrosis is still controversial, with the few available reports being mainly of low quality. While positive findings have been described in many studies, mixed results are still present in the literature in terms of efficacy and adverse events. The difficulties in drawing clear conclusions are also due to the studies heterogeneity, mainly in terms of different BMPs applied, with different concomitant treatments for each bone pathology. Therefore, further research with well-designed studies is needed in order to understand the real potential of this biological approach to favour bone healing.

Platelet-rich plasma for the treatment of bone defects: from pre-clinical rational to evidence in the clinical practice. A systematic review.

PURPOSE: The treatment of large bone defects represents a significant challenge for orthopaedic surgeons. In recent years, biologic agents have also been used to further improve bone healing. Among these, platelet-rich plasma (PRP) is the most exploited strategy. The aim of the present study was to systematically review the available literature to identify: 1) preclinical in-vivo results supporting the rational of PRP use for bone healing; 2) evidence from the clinical practice on the actual clinical benefit of PRP for the treatment of fractures and complications such as delayed unions and non-unions. METHODS: A systematic review of the literature was performed on the application of PRP in bone healing, using the following inclusion criteria: pre-clinical and clinical reports of any level of evidence, written in English language, published in the last 20 years (1996-2016), on the use of PRP to stimulate long-bone defect treatment, with focus on fracture and delayed/non-unions healing. RESULTS: The search in the Pubmed database identified 64 articles eligible for inclusion: 45 were preclinical in-vivo studies and 19 were clinical studies. Despite the fact that the overall pre-clinical results seem to support the benefit of PRP in 91.1 % of the studies, a more in depth analysis underlined a lower success rate, with a positive outcome of 84.4 % in terms of histological analysis, and even lower values considering radiological and biomechanical results (75.0 % and 72.7 % positive outcome respectively). This was also mirrored in the clinical literature, where the real benefit of PRP use to treat fractures and non-unions is still under debate. CONCLUSION: Overall, the available literature presents major limitations in terms of low quality and extreme heterogeneity, which hamper the possibility to optimize PRP treatment and translate it into a real clinical benefit despite positive preclinical findings on its biological potential to favour bone healing.

Scaffold-based cartilage treatments: with or without cells? A systematic review of preclinical and clinical evidence.

PURPOSE: Regenerative scaffold-based procedures are emerging as a potential therapeutic option for the treatment of chondral and osteochondral lesions. In general, we can summarize most of the recent developments to reach clinical application into 2 major trends: the use of different cell sources or the application of biomaterials as a cell-free approach. The aim of this systematic review was to analyze both preclinical and clinical studies on these new trends to understand how the available evidence supports the use of cell sources or justifies the cell-free approach for the scaffold-based treatment of cartilage lesions. METHODS: The research was performed using the PubMed database by looking at studies published in the English language referring to chondral or osteochondral defect repair with scaffold-based procedures until the end of 2013. The following strings were used: ("cartilage"[MeSH] AND "tissue scaffolds"[MeSH]). RESULTS: The search showed an increasing number of published articles each year for both scaffold-based approaches, identifying a total of 305 articles. Among clinical trials, 116 used cell-based scaffold treatments and 11 used scaffolds alone. In the preclinical setting, a scaffold/cell combination was the most used treatment approach (133 v 45 articles), with mesenchymal stem cells (MSCs) being the favorite cell type. Bone marrow was the most used cell source, but other sources are gaining interest. Among articles comparing scaffolds with or without cells, the majority reported superior results for cells (71 of 89 articles). In the clinical setting, most of the articles analyzed chondrocyte-based scaffolds, with only 7 studies using MSCs; all cells were from bone marrow. Despite the lower number of articles, cell-free scaffolds are gaining popularity, with a recent increase in published studies showing promising results. CONCLUSIONS: This systematic review underlined the difficulties in understanding the real need for cells to increase the scaffold-based cartilage healing potential because of the heterogeneity of products used as well as the design of the published studies. Scaffold and cell combinations were the most investigated option in the preclinical setting, showing generally superior results, but in the clinical setting, both strategies remain used. In particular, although chondrocytes are the most commonly used cell type, research showed increasing interest in the potential of MSCs for cartilage regeneration. However, the difficulties in managing cell cultures, together with the development of a new generation of materials able to exploit the intrinsic tissue regeneration ability, justifies the clinical use of cell-free scaffolds, with increasing literature and promising preliminary results. LEVEL OF EVIDENCE: Level IV, systematic review of Level I to IV studies.

Effect of two different preparations of platelet-rich plasma on synoviocytes.

PURPOSE: To analyse the modifications induced by two different platelet-rich plasma (PRP) preparations on osteoarthritis (OA) synoviocytes, by documenting changes in gene expression of factors involved in joint physiopathology. METHODS: OA synoviocytes were cultured for 7 days in medium with different concentrations of either P-PRP (a pure platelet concentrate without leucocytes but with a limited number of platelets), L-PRP (a higher platelet concentrate containing leucocytes) or platelet-poor plasma (PPP). Gene expression of interleukin (IL)-1beta, IL-6, IL-8/CXCL8, tumour necrosis factor alpha, IL-10, IL-4, IL-13, metalloproteinase-13, tissue inhibitor of metalloproteinase (TIMP)-1, (TIMP)-3, (TIMP)-4, vascular endothelial growth factor, transforming growth factor beta1, fibroblast growth factor (FGF)-2, hepatocyte growth factor (HGF), hyaluronic acid (HA) synthases (HAS)-1, (HAS)-2, and (HAS)-3 was analysed by RT-PCR. HA production was determined in culture supernatants by ELISA. RESULTS: IL-1ß, IL-8 and FGF-2 were significantly induced by L-PRP compared to both P-PRP and PPP; HGF was down-modulated by L-PRP versus both P-PRP and PPP, and an inverse dose-response influence was shown for all preparations. Expression level of TIMP-4 was lower in the presence of L-PRP compared with P-PRP. HA production and HAS gene expression did not seem to be modulated by PRP. CONCLUSIONS: L-PRP is able to sustain the up-regulation of proinflammatory factors, (IL-1beta, IL-8 and FGF-2), together with a down-modulation of HGF and TIMP-4 expression, two factors that have been recognized as anti-catabolic mediators in cartilage, thus supporting the need to further optimize the PRP preparations to be applied in clinical practice.

Does PRP enhance bone integration with grafts, graft substitutes, or implants? A systematic review.

BACKGROUND: Several bone implants are applied in clinical practice, but none meets the requirements of an ideal implant. Platelet-rich plasma (PRP) is an easy and inexpensive way to obtain growth factors in physiologic proportions that might favour the regenerative process. The aim of this review is to analyse clinical studies in order to investigate the role of PRP in favouring bone integration of graft, graft substitutes, or implants, and to identify the materials for which the additional use of PRP might be associated with superior osseo- and soft tissues integration. METHODS: A search on PubMed database was performed considering the literature from 2000 to 2012, using the following string: ("Bone Substitutes"[Mesh] OR "Bone Transplantation"[Mesh] OR "Bone Regeneration"[Mesh] OR "Osseointegration"[Mesh]) AND ("Blood Platelets"[Mesh] OR "Platelet-Rich Plasma"[Mesh]). After abstracts screening, the full-texts of selected papers were analyzed and the papers found from the reference lists were also considered. The search focused on clinical applications documented in studies in the English language: levels of evidence included in the literature analysis were I, II and III. RESULTS: Literature analysis showed 83 papers that fulfilled the inclusion criteria: 26 randomized controlled trials (RCT), 14 comparative studies, 29 case series, and 14 case reports. Several implant materials were identified: 24 papers on autologous bone, 6 on freeze-dried bone allograft (FDBA), 16 on bovine porous bone mineral (BPBM), 9 on ß-tricalcium phosphate (ß-TCP), 4 on hydroxyapatite (HA), 2 on titanium (Ti), 1 on natural coral, 1 on collagen sponge, 1 on medical-grade calcium sulphate hemihydrate (MGCSH), 1 on bioactive glass (BG) and 18 on a combination of biomaterials. Only 4 papers were related to the orthopaedic field, whereas the majority belonged to clinical applications in oral/maxillofacial surgery. CONCLUSIONS: The systematic research showed a growing interest in this approach for bone implant integration, with an increasing number of studies published over time. However, knowledge on this topic is still preliminary, with the presence mainly of low quality studies. Many aspects still have to be understood, such as the biomaterials that can benefit most from PRP and the best protocol for PRP both for production and application.

Scaffold-based repair for cartilage healing: a systematic review and technical note.

PURPOSE: The aim of this systematic review was to address the treatment of chondral and osteochondral knee lesions through the use of scaffolds, by showing surgical options and results of this scaffold-based repair approach for the healing of the articular surface. METHODS: All studies published in English addressing cartilage scaffold-based treatment were identified, including those that fulfilled the following criteria: (1) Levels I to IV evidence addressing the outlined areas of interest, (2) measures of functional or clinical outcome, (3) knee cartilage lesions, and (4) minimum of 2 years of follow-up. RESULTS: The analysis showed a progressively increasing number of articles per year from 1995 to February 2012. The number of selected articles was 51, with 40 focusing on 2-step procedures and 11 focusing on 1-step procedures. The evaluation of evidence level showed 3 randomized studies, 10 comparative studies, 33 case series, and 5 case reports. CONCLUSIONS: Regenerative scaffold-based procedures are emerging as a therapeutic option for the treatment of chondral lesions, but well-designed studies are lacking. Systematic long-term evaluation of these techniques and randomized studies are necessary to confirm the potential of this treatment approach, especially compared with the available traditional treatments. Different 1-step scaffold-based strategies are emerging to simplify the procedure and reduce costs. LEVEL OF EVIDENCE: Level IV, systematic review of Level I to IV studies.

Mesenchymal stem cells for the treatment of cartilage lesions: from preclinical findings to clinical application in orthopaedics.

PURPOSE: The aim of this systematic review is to examine the available clinical evidence in the literature to support mesenchymal stem cell (MSC) treatment strategies in orthopaedics for cartilage defect regeneration. METHODS: The research was performed on the PubMed database considering the English literature from 2002 and using the following key words: cartilage, cartilage repair, mesenchymal stem cells, MSCs, bone marrow concentrate (BMC), bone marrow-derived mesenchymal stem cells, bone marrow stromal cells, adipose-derived mesenchymal stem cells, and synovial-derived mesenchymal stem cells. RESULTS: The systematic research showed an increasing number of published studies on this topic over time and identified 72 preclinical papers and 18 clinical trials. Among the 18 clinical trials identified focusing on cartilage regeneration, none were randomized, five were comparative, six were case series, and seven were case reports; two concerned the use of adipose-derived MSCs, five the use of BMC, and 11 the use of bone marrow-derived MSCs, with preliminary interesting findings ranging from focal chondral defects to articular osteoarthritis degeneration. CONCLUSIONS: Despite the growing interest in this biological approach for cartilage regeneration, knowledge on this topic is still preliminary, as shown by the prevalence of preclinical studies and the presence of low-quality clinical studies. Many aspects have to be optimized, and randomized controlled trials are needed to support the potential of this biological treatment for cartilage repair and to evaluate advantages and disadvantages with respect to the available treatments. LEVEL OF EVIDENCE: IV.

Scaffolds for cartilage repair of the ankle joint: The impact on surgical practice.

BACKGROUND: Ideal management of osteochondral lesions in the ankle joint is still theme of debate. Scaffold-based repair is emerging as a new approach for regenerative treatment. METHODS: Articles published in PubMed from 2000 to January 2012 addressing cartilage scaffold-based treatment were identified, including levels I-IV evidence clinical trials with measures of functional, clinical or imaging outcome. RESULTS: The analysis showed a progressively increasing number of articles from 2000. The number of selected papers was 19:15 focusing on two-step and 4 on one-step procedures; no randomized studies, 3 comparative studies, 11 case series and 5 case reports were identified. CONCLUSIONS: Regenerative surgical approach with scaffold-based procedures is emerging as a potential therapeutic option for the treatment of chondral lesions of the ankle. One step treatments simplify the procedure and the results reported are very close to the previous techniques. However, well-designed studies are lacking, and randomized long-term trials are necessary to confirm the potential of these techniques. LEVEL OF EVIDENCE: Review - IV.

Vegetable hierarchical structures as template for bone regeneration: New bio-ceramization process for the development of a bone scaffold applied to an experimental sheep model.

Long bone defects still represent a major clinical challenge in orthopedics, with the inherent loss of function considerably impairing the quality of life of the affected patients. Thus, the purpose of this study was to assess the safety and potential of bone regeneration offered by a load-bearing scaffold characterized by unique hierarchical architecture and high strength, with active surface facilitating new bone penetration and osseointegration in critical size bone defects. The results of this study showed the potential of bio-ceramization processes applied to vegetable hierarchical structures for the production of new wood-derived bone scaffolds, further improved by surface functionalization, with good biological and mechanical properties leading to successful treatment of critical size bone defects in the sheep model. Future studies are needed to evaluate if these scaffolds prototypes, as either biomaterial alone or in combination with augmentation strategies, may represent an optimal solution to enhance bone regeneration in humans.

Secretome and Extracellular Vesicles as New Biological Therapies for Knee Osteoarthritis: A Systematic Review.

Secretome and extracellular vesicles (EVs) are considered a promising option to exploit mesenchymal stem cells' (MSCs) properties to address knee osteoarthritis (OA). The aim of this systematic review was to analyze both the in vitro and in vivo literature, in order to understand the potential of secretome and EVs as a minimally invasive injective biological approach. A systematic review of the literature was performed on PubMed, Embase, and Web of Science databases up to 31 August 2019. Twenty studies were analyzed; nine in vitro, nine in vitro and in vivo, and two in vivo. The analysis showed an increasing interest in this emerging field, with overall positive findings. Promising in vitro results were documented in terms of enhanced cell proliferation, reduction of inflammation, and down-regulation of catabolic pathways while promoting anabolic processes. The positive in vitro findings were confirmed in vivo, with studies showing positive effects on cartilage, subchondral bone, and synovial tissues in both OA and osteochondral models. However, several aspects remain to be clarified, such as the different effects induced by EVs and secretome, which is the most suitable cell source and production protocol, and the identification of patients who may benefit more from this new biological approach for knee OA treatment.

The Role of Three-Dimensional Scaffolds in Treating Long Bone Defects: Evidence from Preclinical and Clinical Literature-A Systematic Review.

Long bone defects represent a clinical challenge. Bone tissue engineering (BTE) has been developed to overcome problems associated with conventional methods. The aim of this study was to assess the BTE strategies available in preclinical and clinical settings and the current evidence supporting this approach. A systematic literature screening was performed on PubMed database, searching for both preclinical (only on large animals) and clinical studies. The following string was used: "(Scaffold OR Implant) AND (Long bone defect OR segmental bone defect OR large bone defect OR bone loss defect)." The search retrieved a total of 1573 articles: 51 preclinical and 4 clinical studies were included. The great amount of preclinical papers published over the past few years showed promising findings in terms of radiological and histological evidence. Unfortunately, this in vivo situation is not reflected by a corresponding clinical impact, with few published papers, highly heterogeneous and with small patient populations. Several aspects should be further investigated to translate positive preclinical findings into clinical protocols: the identification of the best biomaterial, with both biological and biomechanical suitable properties, and the selection of the best choice between cells, GFs, or their combination through standardized models to be validated by randomized trials.

Stem cells in articular cartilage regeneration.

Mesenchymal stem cells (MSCs) have emerged as a promising option to treat articular defects and early osteoarthritis (OA) stages. However, both their potential and limitations for a clinical use remain controversial. Thus, the aim of this systematic review was to examine MSCs treatment strategies in clinical settings, in order to summarize the current evidence of their efficacy for the treatment of cartilage lesions and OA.Among the 60 selected studies, 7 were randomized, 13 comparative, 31 case series, and 9 case reports; 26 studies reported the results after injective administration, whereas 33 used surgical implantation. One study compared the two different modalities. With regard to the cell source, 20 studies concerned BMSCs, 17 ADSCs, 16 BMC, 5 PBSCs, 1 SDSCs, and 1 compared BMC versus PBSCs. Overall, despite the increasing literature on this topic, the evidence is still limited, in particular for high-level studies. On the other hand, the available studies allow to draw some indications. First, no major adverse events related to the treatment or to the cell harvest have been reported. Second, a clinical benefit of using MSCs therapies has been reported in most of the studies, regardless of cell source, indication, or administration method. This effectiveness has been reflected by clinical improvements and also positive MRI and macroscopic findings, whereas histologic features gave more controversial results among different studies. Third, young age, lower BMI, smaller lesion size for focal lesions, and earlier stages of OA joints have been shown to correlate with better outcomes, even though the available data strength does not allow to define clear cutoff values. Finally, definite trends can be observed with regard to the delivery method: currently cultured cells are mostly being administered by i.a. injection, while one-step surgical implantation is preferred for cell concentrates. In conclusion, while promising results have been shown, the potential of these treatments should be confirmed by reliable clinical data through double-blind, controlled, prospective and multicenter studies with longer follow-up, and specific studies should be designed to identify the best cell sources, manipulation, and delivery techniques, as well as pathology and disease phase indications.