Fiber Thickness and Porosity Control in a Biopolymer Scaffold 3D Printed through a Converted Commercial FDM Device

3D printing has opened exciting new opportunities for the in vitro fabrication of biocompatible hybrid pseudo-tissues. Technologies based on additive manufacturing herald a near future when patients will receive therapies delivering functional tissue substitutes for the repair of their musculoskeletal tissue defects. In particular, bone tissue engineering (BTE) might extensively benefit from such an approach. However, designing an optimal 3D scaffold with adequate stiffness and biodegradability properties also guaranteeing the correct cell adhesion, proliferation, and differentiation, is still a challenge. The aim of this work was the rewiring of a commercial fuse deposition modeling (FDM) 3D printer into a 3D bioplotter, aiming at obtaining scaffold fiber thickness and porosity control during its manufacturing. Although it is well-established that FDM is a fast and low-price technology, the high temperatures required for printing lead to limitations in the biomaterials that can be used. In our hands, modifying the printing head of the FDM device with a custom-made holder has allowed to print hydrogels commonly used for embedding living cells. The results highlight a good resolution, reproducibility and repeatability of alginate/gelatin scaffolds obtained via our custom 3D bioplotter prototype, showing a viable strategy to equip a small-medium laboratory with an instrument for manufacturing good-quality 3D scaffolds for cell culture and tissue engineering applications

Quality Control Platform for the Standardization of a Regenerative Medicine Product

Adipose tissue is an attractive source of stem cells due to its wide availability. They contribute to the stromal vascular fraction (SVF), which is composed of pre-adipocytes, tissue-progenitors, and pericytes, among others. Because its direct use in medical applications is increasing worldwide, new quality control systems are required. We investigated the ability of the Non-Equilibrium Earth Gravity Assisted Dynamic Fractionation (NEEGA-DF) method to analyze and separate cells based solely on their physical characteristics, resulting in a fingerprint of the biological sample. Adipose tissue was enzymatically digested, and the SVF was analyzed by NEEGA-DF. Based on the fractogram (the UV signal of eluting cells versus time of analysis) the collection time was set to sort alive cells. The collected cells (F-SVF) were analyzed for their phenotype, immunomodulation ability, and differentiation potential. The SVF profile showed reproducibility, and the alive cells were collected. The F-SVF showed intact adhesion phenotype, proliferation, and differentiation potential. The methodology allowed enrichment of the mesenchymal component with a higher expression of mesenchymal markers and depletion of debris, RBCs, and an extracellular matrix still present in the digestive product. Moreover, cells eluting in the last minutes showed higher circularity and lower area, proving the principles of enrichment of a more homogenous cell population with better characteristics. We proved the NEEGA-DF method is a "gentle" cell sorter that purifies primary cells obtained by enzymatic digestion and does not alter any stem cell function

Lights and shadows concerning platelet products for musculoskeletal regeneration.

Various types of platelet (PLT) products, such as Platelet Rich Plasma (PRP) and Platelet Gel (PG), derived from autologous peripheral blood, have been used for tissue repair. The good clinical outcomes, due mainly to their safety and Growth Factor (GF) content, have led to a wide use of PLT products in many fields of medicine. However, until now the existing literature adds controversies to the use of PLT concentrates. When talking about PLTs and their products, a great number of variables have to be considered. These variables are mainly related to PRP preparation methods, the type of activators, intra- and inter-species variability, types of pathology to be treated, the ways and times of administration and the association of PRP or PG with other treatments. This review considers and discusses these causes of variability with particular attention to orthopaedic implications. The possibility of improving the knowledge on variables affecting therapeutic efficacy will surely help in addressing the best combination of factors implied in the different steps of PLT concentrate preparation and use

Ultrastructural modifications of human meniscus under different conditions

Human meniscus presents two cell populations [1]. The main cell type present in its inner and middle part is the fibrochondrocyte, a round or oval shaped cell, while in outer zone fibroblast-like cells within a dense connective tissue [2] are mostly observable. The aim of this work is to study a variety of pathological conditions. We have analized samples of meniscus obtained from 3 multiorgan donors (63 median age, years), 5 patients with traumatic meniscal tear (40 median age, years) and from 3 patients undergoing total knee replacement for osteoartritis (OA) (73 median age, years). In elderly menisci we observed a progression of chromatin margination, and a partial cytoplasmic organelle conservation, but for the presence of occasional autophagic vacuoles. Both after trauma and in OA, an increasing chromatin condensation, organelle degeneration and cytoplasmic vacuolization appear. In OA, similarly to elderly, autophagic vacuoles, which probably represent a cellular self-protection mechanism, appeared in the cytoplasm. The most evident ultrastructural changes have been observed when intervention takes place long time after trauma. In this case a high chromatin condensation, a large cytoplasmic vacuolization with degeneration of organelles and several necrotic cells appear. Calcification areas occur in all conditions. In particular, specimens from traumatic menisci have a structure similar to OA ones, especially if trauma has not been surgically repaired at appropriate times. In all there is disorganization of collagen fibers, and their replacement with proteoglycans. We can conclude that trauma and OA induce an increasing meniscal degeneration, comparable to physiological aging. When surgery takes place long time after trauma we observed most evident menisci degeneration. In all pathological conditions apoptotic like features appeared [3]

A Comprehensive Microstructural and Compositional Characterization of Allogenic and Xenogenic Bone: Application to Bone Grafts and Nanostructured Biomimetic Coatings

Bone grafts and bone-based materials are widely used in orthopedic surgery. However, the selection of the bone type to be used is more focused on the biological properties of bone sources than physico-chemical ones. Moreover, although biogenic sources are increasingly used for deposition of biomimetic nanostructured coatings, the influence of specific precursors used on coating’s morphology and composition has not yet been explored. Therefore, in order to fill this gap, we provided a detailed characterization of the properties of the mineral phase of the most used bone sources for allografts, xenografts and coating deposition protocols, not currently available. To this aim, several bone apatite precursors are compared in terms of composition and morphology. Significant differences are assessed for the magnesium content between female and male human donors, and in terms of Ca/P ratio, magnesium content and carbonate substitution between human bone and different animal bone sources. Prospectively, based on these data, bone from different sources can be used to obtain bone grafts having slightly different properties, depending on the clinical need. Likewise, the suitability of coating-based biomimetic films for specific clinical musculoskeletal application may depend on the type of apatite precursor used, being differently able to tune surface morphology and nanostructuration, as shown in the proof of concepts of thin film manufacturing here presented

Virtual Surgical Planning, 3D-Printing and Customized Bone Allograft for Acute Correction of Severe Genu Varum in Children

Complex deformities of lower limbs are frequent in children with genetic or metabolic skeletal disorders. Early correction is frequently required, but it is technically difficult and burdened by complications and recurrence. Herein, we described the case of a 7-year-old girl affected by severe bilateral genu varum due to spondyloepiphyseal dysplasia. The patient was treated by patient-specific osteotomies and customized structural wedge allograft using Virtual Surgical Planning (VSP) and 3D-printed patient-specific instrumentation (PSI). The entire process was performed through an in-hospital 3D-printing Point-of-Care (POC). VSP and 3D-printing applied to pediatric orthopedic surgery may allow personalization of corrective osteotomies and customization of structural allografts by using low-cost in-hospital POC. However, optimal and definitive alignment is rarely achieved in such severe deformities in growing skeleton through a single operation

Human tissue culture of osteochondral defect: An advanced in vitro model

The optimization of advanced in vitro models is essential for the development of alternative methods. The in vitro study of osteochondral regeneration still has numerous limitations and wide scope for exploration

Being active with a total hip or knee prosthesis: a systematic review into physical activity and sports recommendations and interventions to improve physical activity behavior

Objectives Regular physical activity (PA) is considered important after total hip and knee arthroplasty (THA/TKA). Objective was to systematically assess literature on recommendations given by healthcare professionals to persons after THA and TKA and to provide an overview of existing interventions to stimulate PA and sports participation. Methods A systematic review with a narrative synthesis including articles published between January 1995 and January 2021 reporting on recommendations and interventions. The PubMed, Embase, CINAHL and PsycInfo databases were systematically searched for original articles reporting on physical activity and sports recommendations given by healthcare professionals to persons after THA and TKA, and articles reporting on interventions/programs to stimulate a physically active lifestyle after rehabilitation or explicitly defined as part of the rehabilitation. Methodological quality was assessed with the Mixed Methods Appraisal Tool (MMAT). The review was registered in Prospero (PROSPERO:CRD42020178556). Results Twenty-one articles reported on recommendations. Low-impact activities were allowed. Contact sports, most ball sports, and martial arts were not recommended. One study informed on whether health-enhancing PA recommendations were used to stimulate persons to become physically active. No studies included recommendations on sedentary behavior. Eleven studies reported on interventions. Interventions used guidance from a coach/physiotherapist; feedback on PA behavior from technology; and face-to-face, education, goal-setting, financial incentives and coaching/financial incentives combined, of which feedback and education seem to be most effective. For methodological quality, 18 out of 21 (86%) articles about recommendations and 7 out of 11 (64%) articles about interventions scored yes on more than half of the MMAT questions (0-5 score). Conclusion There is general agreement on what kind of sports activities can be recommended by healthcare professionals like orthopedic surgeons and physiotherapists. No attention is given to amount of PA. The same is true for limiting sedentary behavior. The number of interventions is limited and diverse, so no conclusions can be drawn. Interventions including provision of feedback about PA, seem to be effective and feasible