Bone defects can result from different incidents such as acute trauma, infection or tumor resection. While in most instances bone healing can be achieved given the tissue's innate ability of self-repair, for critical-sized defects spontaneous regeneration is less likely to occur, therefore requiring surgical intervention. Current clinical procedures have failed to adequately address this issue. For this reason, bone tissue engineering (BTE) strategies involving the use of synthetic grafts for replacing damaged bone and promoting the tissue's regeneration are being investigated. The electrical stimulation (ES) of bone defects using direct current has yielded very promising results, with neo tissue formation being achieved in the target sites
Electrospinning is an advantageous technique for cartilage tissue engineering (CTE) applications due to its ability to produce nanofibers recapitulating the size and alignment of the collagen fibers present within the articular cartilage superficial zone. Moreover, coaxial electrospinning allows the fabrication of core-shell fibers able to encapsulate and release bioactive molecules in a sustained manner. Kartogenin (KTG) is a small heterocyclic molecule, which was demonstrated to promote the chondrogenic differentiation of human bone marrow-derived mesenchymal stem/stromal cells(hBMSCs)[1]. In this work, we developed and evaluated the biological performance of core-shell poly(glycerol sebacate)(PGS)/poly(caprolactone)(PCL) aligned nanofibers (core:PGS/shell:PCL) mimicking the native articular cartilage extracellular matrix(ECM) and able to promote the sustained release of the chondroinductive drug KTG[2]. The produced coaxial aligned PGS/PCL scaffolds were characterized in terms of their structure and fiber diameter, chemical composition, thermal properties, mechanical performance under tensile testing and in vitro degradation kinetics, in comparison to monoaxial PCL aligned fibers and respective non-aligned controls. KTG was incorporated into the core PGS solution to generate core-shell PGS-KTG/PCL nanofibers and its release kinetics was studied by HPLC analysis. KTG-loaded electrospun aligned scaffolds capacity to promote hBMSCs chondrogenic differentiation was evaluated by assessing cell proliferation, typical cartilage-ECM production (sulfated glycosaminiglycans(sGAG)) and chondrogenic marker genes expression in comparison to non-loaded controls. All the scaffolds fabricated showed average fiber diameters within the nanometer-scale and the core-shell structure of the fibers was clearly confirmed by TEM. The coaxial PGS-KTG/PCL nanofibers evidenced a more sustained drug release over 21 days. Remarkably, in the absence of the chondrogenic cytokine TGF-β3, KTG-loaded nanofibers promoted significantly the proliferation and chondrogenic differentiation of hBMSCs, as suggested by the increased cell numbers, higher sGAG amounts and up-regulation of the chondrogenic genes COL2A1, Sox9, ACAN and PRG4 expression. Overall, our results highlight the potential of core-shell PGS-KTG/PCL aligned nanofibers for the development of novel MSC-based CTE strategies.
The growing number of non-union fractures in an aging population has increased the clinical demand for tissue-engineered bone. Electrical stimulation (ES) has been described as a promising strategy for bone regeneration treatments in several clinical studies. However the underlying mechanism by which ES augments bone formation is still poorly understood and its use in bone tissue engineering (BTE) strategies is currently underexplored. Additive manufacturing (AM) technologies (Fused Deposition Modeling/3D Printing) have been widely used in BTE due to their ability to fabricate scaffolds with a high control over their structural and mechanical properties in a reproducible and scalable manner. Thus, in this work, we combined AM methods with conductive biomaterials and ES to enhance the osteogenic differentiation of human bone marrow-derived mesenchymal stem/stromal cells (hBMSCs) envisaging improved BTE strategies. First, we started by developing AM-based electro-bioreactor devices containing medical-grade electrodes (stainless steel and Ti6Al4V) to apply ES to monolayer 2D cultures and 3D cell-seeded scaffolds. Computer modeling(Finite Element Analysis-FEA) was employed to predict the magnitude/distribution of electrical fields within the ES devices and along the different conductive scaffolds. Prior to scaffold culture, 5 different ES protocols were tested in terms of their ability to promote hBMSCs proliferation and osteogenic differentiation in 2D cultures. The best performance ES protocol was then used in two different AM-based BTE strategies: 1) Two different conductive scaffolds (conductive poly lactic acid (PLA) and titanium) were seeded with hBMSCs and cultured for 21 days under osteogenic medium conditions with and without ES and their biological performance was evaluated in comparison to non-conductive standard PLA scaffolds; 2) Different PEDOT:PSS-based coating solutions were screened to obtain PEDOT:PSS/Gelatin-coated 3D polycaprolactone (PCL) scaffolds with a high(11 S.cm-1) and stable electroconductivity. When cultured under ES, PEDOT:PSS/Gelatin-PCL scaffolds enhanced significantly hBMSCs osteogenic differentiation and mineralization(calcium deposition), highlighting their potential for BTE applications.
Acute septic arthritis of the knee can lead to joint damage or sepsis, if early diagnosis and treatment fail to occur, which includes drainage of the joint, adequate antibiotic coverage and resting of the knee. Classically, drainage of the knee was performed either with multiple aspirations or open arhtrotomy. The arthroscopic approach has becoming widely accepted, as it allows adequate drainage of the pus and debridement with partial or total sinovectomy of the joint. The aim of this study was to evaluate the differences between arthroscopy and open arthrotomy in the clinical outcomes and rate of recurrence in patients with septic arthritis of the knee joint. We reviewed patients with acute septic arthritis of the knee admitted in our center between January 2010 and December 2014. The criteria for diagnosis was report of purulent material when arhtrotomy or arthroscopy was performed or a positive culture of the joint fluid. Patients with recent surgery or documented osteomyelitis of the femur or tíbia were excluded. We used the Oxford Knee Score (OKS) to classify the clinical outcomes in the end of follow-up, and registered the rate of recurrence in each group. The statistical evaluation of the results was performed using Student's t-test. 65 patients were treated during this period, 37 by an open arthrotomy through a lateral supra-patellar aproach, and 28 by arthroscopy through 2 standard anterior portals. All the patients were imobilized with a cast or orthosis in the immediate post-operation period for a mean period of 13 days in the arthrotomy group (8–15) and 9 days in the arthroscopy group (6–12) and received endovenous antibiotics for at least 10 days, followed by oral antibiotics for a mean total of 36 days in the the arthrotomy group (30–48) and 32 days in the arthroscopy group (22–36). The mean follow-up was 22 months in the arthrotomy group (8–28 months) and 18 months in the arthroscopy group (14–24). The mean OKS was 31 in the the arthrotomy group (21–39) and 35 in the arthroscopy group (25–44). There was 1 recurrence in the arthrotomy group and 1 recurrence in the arthroscopic group, both managed by knee arthrotomy. Drainage is a key step in treatment of knee pyoarthrosis, either through an open or an arthroscopic approach. Both seem to be equally effective, with no significant statistical difference in terms of recurrence. The functional results tend to favour the arthroscopic approach, but with no statistical significance.
