Biomaterial and biocompatibility evaluation of tunicate nanocellulose for tissue engineering

Extracellular matrix fibril components, such as collagen, are crucial for the structural properties of several tissues and organs. Tunicate-derived cellulose nanofibrils (TNC) combined with living cells could become the next gold standard for cartilage and soft-tissue repair, as TNC fibrils present similar dimensions to collagen, feasible industrial production, and chemically straightforward and cost-efficient extraction procedures. In this study, we characterized the physical properties of TNC derived from aquaculture production in Norwegian fjords and evaluated its biocompatibility regarding induction of an inflammatory response and foreign-body reactions in a Wistar rat model. Additionally, histologic and immunohistochemical analyses were performed for comparison with expanded polytetrafluoroethylene (ePTFE) as a control. The average length of the TNC as determined by atomic force microscopy was tunable from 3 mu m to 2.4 mu m via selection of a various number of passages through a microfluidizer, and rheologic analysis showed that the TNC hydrogels were highly shear-thinning and with a viscosity dependent on fibril length and concentration. As a bioink, TNC exhibited excellent rheological and printability properties, with constructs capable of being printed with high resolution and fidelity. We found that post-print cross-linking with alginate stabilized the construct shape and texture, which increased its ease of handling during surgery. Moreover, after 30 days in vivo, the constructs showed a highly-preserved shape and fidelity of the grid holes, with these characteristics preserved after 90 days and with no signs of necrosis, infection, acute inflammation, invasion of neutrophil granulocytes, or extensive fibrosis. Furthermore, we observed a moderate foreign-body reaction involving macrophages, lymphocytes, and giant cells in both the TNC constructs and PTFE controls, although TNC was considered a nonirritant biomaterial according to ISO 10993-6 as compared with ePTFE. These findings represent a milestone for future clinical application of TNC scaffolds for tissue repair. One sentence summary: In this study, the mechanical properties of tunicate nanocellulose are superior to nanocellulose extracted from other sources, and the biocompatibility is comparable to that of ePTFE

Long-term in vivo integrity and safety of 3D-bioprinted cartilaginous constructs

Long-term stability and biological safety are crucial for translation of 3D-bioprinting technology into clinical applications. Here, we addressed the long-term safety and stability issues associated with 3D-bioprinted constructs comprising a cellulose scaffold and human cells (chondrocytes and stem cells) over a period of 10 months in nude mice. Our findings showed that increasing unconfined compression strength over time significantly improved the mechanical stability of the cell-containing constructs relative to cell-free scaffolds. Additionally, the cell-free constructs exhibited a mean compressive stress and stiffness (compressive modulus) of 0.04 +/- 0.05 MPa and 0.14 +/- 0.18 MPa, respectively, whereas these values for the cell-containing constructs were 0.11 +/- 0.08 MPa (p= .019) and 0.53 +/- 0.59 MPa (p= .012), respectively. Moreover, histomorphologic analysis revealed that cartilage formed from the cell-containing constructs harbored an abundance of proliferating chondrocytes in clusters, and after 10 months, resembled native cartilage. Furthermore, extension of the experiment over the complete lifecycle of the animal model revealed no signs of ossification, fibrosis, necrosis, or implant-related tumor development in the 3D-bioprinted constructs. These findings confirm the in vivo biological safety and mechanical stability of 3D-bioprinted cartilaginous tissues and support their potential translation into clinical applications

Do patients or their physicians more accurately assess long-term risk associated with hypertension? A population-based study

Objective: To compare the assessments of 10-year probability by patients and their physicians of cardiovascular complications of hypertension with actual outcomes. Design: Patients with uncomplicated hypertension treated with at least one antihypertensive drug at inclusion were followed for 10 years through mandatory national health registers. Setting: 55 primary health care centres, 11 hospital outpatient clinics in Sweden Patients: 848 patient, 212 physicians. Main outcome measures: Patients and physicians estimated the probability of hypertension-related complications with treatment (death, heart failure, acute myocardial infarction/AMI, and stroke) for each patient in 848 pairs. Estimates were compared with the clinical outcomes 10 years later using data from the Mortality Register and the National Patient Register. Results: Patients were significantly better (p &amp;lt; 0.001) than their physicians in estimating the average probability of heart failure compared with actual outcome data (14% vs. 24%, outcome 15%), AMI (16% vs. 26%, outcome 8%), and stroke (15% vs. 25%, outcome 11%). Patients were significantly worse (p &amp;lt; 0.001) at estimating the average probability of death (10% vs. 18%, actual outcome 20%). Neither the patients nor the physicians were able to distinguish reliably between low-risk and high-risk patients after adjustment for age and sex. Conclusions: Patients were better than their physicians in estimating the average probability of morbidity due to hypertension. Both the patients and their attending physicians had difficulty in estimating the individual patients risk of complications. The results support the use of evidence-based tools in consultations for assessing the risk of cardiovascular complications associated with hypertension.Funding Agencies|Merck Co. Inc.Merck &amp; Company; Linkoping University; Medical Research Council of Southeast Sweden (FORSS); University of Gothenburg (LUA); NEPI Foundation; Faculty of Medicine and Health Sciences, Linkoping University, Sweden</p