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This work describes the preparation and characterization of biomimetic chitosan/multiwall carbon nanotubes/nano-hydroxyapatite (CTS/MWCNT/nHAp) scaffolds and their viability for bone tissue engineering applications. The cryogenic process ice segregation-induced self-assembly (ISISA) was used to fabricate 3D biomimetic CTS scaffolds. Proper combination of cryogenics, freeze-drying, nature and molecular ratio of solutes give rise to 3D porous interconnected scaffolds with clusters of nHAp distributed along the scaffold surface. The effect of doping in CNT (e.g. with oxygen and nitrogen atoms) on cell viability was tested. Under the same processing conditions, pore size was in the range of 20-150 μm and irrespective on the type of CNT. Studies on cell viability with scaffolds were carried out using human cells from periosteum biopsy. Prior to cell seeding, the immunophenotype of mesenchymal periosteum or periosteum-derived stem cells (MSCs-PCs) was characterized by flow cytometric analysis using fluorescence-activated and characteristic cell surface markers for MSCs-PCs. The characterized MSCs-PCs maintained their periosteal potential in cell cultures until the 2nd passage from primary cell culture. Thus, the biomimetic CTS/MWCNT/nHAp scaffolds demonstrated good biocompatibility and cell viability in all cases such that it can be considered as promising biomaterials for bone tissue engineering.

BackgroundTreatment of severe or chronic skin wounds is an important challenge facing medicine and a significant health care burden. Proper wound healing is often affected by bacterial infection; where biofilm formation is one of the main risks and particularly problematic because it confers protection to microorganisms against antibiotics. One avenue to prevent bacterial colonization of wounds is the use of silver nanoparticles (AgNPs); which have proved to be effective against non-multidrug-resistant and multidrug-resistant bacteria. In addition, the use of mesenchymal stem cells (MSC) is an excellent option to improve wound healing due to their capability for differentiation and release of relevant growth factors. Finally, radiosterilized pig skin (RPS) is a biomatrix successfully used as wound dressing to avoid massive water loss, which represents an excellent carrier to deliver MSC into wound beds. Together, AgNPs, RPS and MSC represent a potential dressing to control massive water loss, prevent bacterial infection and enhance skin regeneration; three essential processes for appropriate wound healing with minimum scaring.ResultsWe synthesized stable 10 nm-diameter spherical AgNPs that showed 21- and 16-fold increase in bacteria growth inhibition (in comparison to antibiotics) against clinical strains Staphylococcus aureus and Stenotrophomonas maltophilia, respectively. RPS samples were impregnated with different AgNPs suspensions to develop RPS-AgNPs nanocomposites with different AgNPs concentrations. Nanocomposites showed inhibition zones, in Kirby–Bauer assay, against both clinical bacteria tested. Nanocomposites also displayed antibiofilm properties against S. aureus and S. maltophilia from RPS samples impregnated with 250 and 1000 ppm AgNPs suspensions, respectively. MSC were isolated from adipose tissue and seeded on nanocomposites; cells survived on nanocomposites impregnated with up to 250 ppm AgNPs suspensions, showing 35% reduction in cell viability, in comparison to cells on RPS. Cells on nanocomposites proliferated with culture days, although the number of MSC on nanocomposites at 24 h of culture was lower than that on RPS.ConclusionsAgNPs with better bactericide activity than antibiotics were synthesized. RPS-AgNPs nanocomposites impregnated with 125 and 250 ppm AgNPs suspensions decreased bacterial growth, decreased biofilm formation and were permissive for survival and proliferation of MSC; constituting promising multi-functional dressings for successful treatment of skin wounds.Electronic supplementary materialThe online version of this article (10.1186/s12951-017-0331-0) contains supplementary material, which is available to authorized users.

Background: Few randomized controlled trials with a midterm follow-up have compared matrix-assisted autologous chondrocyte transplantation (MACT) with microfracture (MFx) for knee cartilage lesions. Purpose: To compare the structural, clinical, and safety outcomes at midterm follow-up of MACT versus MFx for treating symptomatic knee cartilage lesions. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 48 patients aged between 18 and 50 years, with 1- to 4-cm2 International Cartilage Repair Society (ICRS) grade III to IV knee chondral lesions, were randomized in a 1:1 ratio to the MACT and MFx treatment groups. A sequential prospective evaluation was performed using magnetic resonance imaging (MRI) T2 mapping, the MOCART (magnetic resonance observation of cartilage repair tissue) score, second-look arthroscopic surgery, patient-reported outcome measures, the responder rate (based on achieving the minimal clinically important difference for the Knee injury and Osteoarthritis Outcome Score [KOOS] pain and KOOS Sport/Recreation), adverse events, and treatment failure (defined as a reoperation because of symptoms caused by the primary defect and the detachment or absence of >50% of the repaired tissue during revision surgery). Results: Overall, 35 patients (18 MACT and 17 MFx) with a mean chondral lesion size of 1.8 ± 0.8 cm2 (range, 1-4 cm2) were followed up to a mean of 6 years postoperatively (range, 4-9 years). MACT demonstrated significantly better structural outcomes than MFx at 1 to 6 years postoperatively. At final follow-up, the MRI T2 mapping values of the repaired tissue were 37.7 ± 8.5 ms for MACT versus 46.4 ± 8.5 ms for MFx ( P = .003), while the MOCART scores were 59.4 ± 17.3 and 42.4 ± 16.3, respectively ( P = .006). More than 50% defect filling was seen in 95% of patients at 2 years and 82% at 6 years in the MACT group and in 67% at 2 years and 53% at 6 years in the MFx group. The second-look ICRS scores at 1 year were 10.7 ± 1.3 for MACT and 9.0 ± 1.8 for MFx ( P = .001). Both groups showed significant clinical improvements at 6 years postoperatively compared with their preoperative status. Significant differences favoring the MACT group were observed at 2 years on the KOOS Activities of Daily Living ( P = .043), at 4 years on all KOOS subscales (except Symptoms; P < .05) and the Tegner scale ( P = .008), and at 6 years on the Tegner scale ( P = .010). The responder rates at 6 years were 53% and 77% for MFx and MACT, respectively. There were no reported treatment failures after MACT; the failure rate was 8.3% in the MFx group. Neither group had serious adverse events related to treatment. Conclusion: Patients who underwent MACT had better structural outcomes than those who underwent MFx at 1 to 6 years postoperatively. Both groups of patients showed significant clinical improvements at final follow-up compared with their preoperative status. MACT showed superiority at 4 years for the majority of the KOOS subscales and for the Tegner scale at 4 to 6 years. The MACT group also had a higher responder rate and lower failure rate at final follow-up. Registration: NCT01947374 ( ClinicalTrials.gov identifier).

Background Complex meniscal lesions often require meniscectomy with favorable results in the short term but a high risk of early osteoarthritis subsequently. Partial meniscectomy treated with meniscal substitutes may delay articular cartilage degeneration. Purpose To evaluate the status of articular cartilage by T2 mapping after meniscal substitution with polyurethane scaffolds enriched with mesenchymal stem cells (MSC) and comparison with acellular scaffolds at 12 months. Methods Seventeen patients (18-50 years) with past meniscectomies were enrolled in 2 groups: (1) acellular polyurethane scaffold (APS) or (2) polyurethane scaffold enriched with MSC (MPS). Patients in the MPS group received filgrastim to stimulate MSC production, and CD90+ cells were obtained and cultured in the polyurethane scaffold. The scaffolds were implanted arthroscopically into partial meniscus defects. Concomitant injuries (articular cartilage lesions or cartilage lesions) were treated during the same procedure. Changes in the quality of articular cartilage were evaluated with T2 mapping in femur and tibia at 12 months. Results In tibial T2 mapping, values for the MPS group increased slightly at 9 months but returned to initial values at 12 months ( P > 0.05). In the APS group, a clear decrease from 3 months to 12 months was observed ( P > 0.05). This difference tended to be significantly lower in the APS group compared with the MPS group at the final time point ( P = 0.18). In the femur, a slight increase in the MPS group (47.8 ± 3.4) compared with the APS group (45.3 ± 4.9) was observed ( P > 0.05). Conclusion Meniscal substitution with polyurethane scaffold maintains normal T2 mapping values in adjacent cartilage at 12 months. The addition of MSC did not show any advantage in the protection of articular cartilage over acellular scaffolds ( P > 0.05).

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Interest in novel delivery systems that improve the cytoprotective and antioxidant effects of natural drugs has been explored recently due to the increase in the incidence of chronic diseases in which oxidation mechanisms are involved. Curcumin is a phenolic compound recently shown to be clinically significant due to its anti-inflammatory, anticancer, and antioxidant properties. However, this molecule possesses a low bioavailability and a high degradation rate in the presence of light. Therefore, we prepared nanoparticles of poly-ε-caprolactone and Pluronic® F-68 as a stabilizer and loaded these with curcumin (Cur–PCL nanoparticles) for antioxidant and cytoprotective applications. The nanoparticles did not induce cell death, but they did reduce cell proliferation without affecting cell migration and cell adhesion. Interestingly, Cur–PCL and poly-ε-caprolactone nanoparticles reduced the oxidative stress induced by hydrogen peroxide and presented a cytoprotective effect. Remarkably, poly-ε-caprolactone nanoparticles showed a decrement of 30% in reactive oxygen species presence compared to the positive control. The decrease of reactive oxygen species derived from the administration of poly-ε-caprolactone nanoparticles could be attributed to the presence of Pluronic® F-68. Taken together, these data indicated that these nanoparticles might have a clinical application in disorders related to reactive oxygen species formation.

Skin wound repair requires the development of different kinds of biomaterials that must be capable of restoring the damaged tissue. Type I collagen and chitosan have been widely used to develop scaffolds for skin engineering because of their cell-related signaling properties such as proliferation, migration, and survival. Collagen is the major component of the skin extracellular matrix (ECM), while chitosan mimics the structure of the native polysaccharides and glycosaminoglycans in the ECM. Chitosan and its derivatives are also widely used as drug delivery vehicles since they are biodegradable and noncytotoxic. Regulation of the inflammatory response is crucial for wound healing and tissue regeneration processes; and, consequently, the development of biomaterials such as hydrogels with anti-inflammatory properties is very important and permissive for the growth of cells. In the last years, it has been shown that mesenchymal stem cells have clinical importance in the treatment of different pathologies, for example, skin injuries. In this paper, we describe the anti-inflammatory activity of collagen type 1/chitosan/dexamethasone hydrogel, which is permissive for the culture of human adipose-derived mesenchymal stem cells (hADMSC). Our results show that hADMSC cultured in the hydrogel are viable, proliferate, and secrete the anti-inflammatory cytokine interleukin-10 (IL-10) but not the inflammatory cytokine Tumor Necrosis Factor-alpha (TNF-α).