A New Bioactive Fibrin Formulation Provided Superior Cartilage Regeneration in a Caprine Model.

The effective and long-term treatment of cartilage defects is an unmet need among patients worldwide. In the past, several synthetic and natural biomaterials have been designed to support functional articular cartilage formation. However, they have mostly failed to enhance the terminal stage of chondrogenic differentiation, leading to scar tissue formation after the operation. Growth factors substantially regulate cartilage regeneration by acting on receptors to trigger intracellular signaling and cell recruitment for tissue regeneration. In this study, we investigated the effect of recombinant insulin-like growth factor 1 (rIGF-1), loaded in fibrin microbeads (FibIGF1), on cartilage regeneration. rIGF-1-loaded fibrin microbeads were injected into full-thickness cartilage defects in the knees of goats. The stability, integration, and quality of tissue repair were evaluated at 1 and 6 months by gross morphology, histology, and collagen type II staining. The in vivo results showed that compared to plain fibrin samples, particularly at 6 months, FibIGF1 improved the functional cartilage formation, confirmed through gross morphology, histology, and collagen type II immunostaining. FibIGF1 could be a promising candidate for cartilage repair in the clinic.

Pediatric phalanx fractures: A retrospective study and review of the literature.

Purpose: Conventional radiography is frequently performed in pediatric patients in whom finger fractures are suspected. However, until now, the rate of positive findings of finger radiographic examinations in pediatric patients is unknown. This study aimed to evaluate the number of positive findings in the standard radiographic examinations of finger injuries in pediatric patients in a Level 1 trauma center systematically. Methods: We conducted a retrospective study on all children 0-16 years old admitted for acute finger injury in the Emergency Department of a University Hospital during the first semester of 2019 and received a radiographic examination. Their demographic characteristics, fracture pattern, and treatment were then analyzed and interpreted. Results: Out of 478 finger injuries reviewed in this cohort, 160 X-rays revealed positive for a fracture giving a fracture rate of 33.5%. More than half of them (51.9%) occurred in the age group of adolescents (11-16 years). Among all finger fractures, only 3.8% of them treated surgically. Conclusion: In this study, a relevant amount of standard finger radiographs revealed a low fracture rate and a rare operative indication of 3.8%. Therefore, indications for X-rays should be reviewed properly and alternative procedures should be discussed. Clinical decision rules should be developed and the necessary pathways must be implemented to minimize radiation exposure, waiting time, and costs.Level of evidence: level IV.

A Single Retrograde Intramedullary Nail Technique for Treatment of Displaced Proximal Humeral Fractures in Children: Case Series and Review of the Literature.

Displaced proximal humeral fractures in older children with low remodeling potential need to be reduced and fixed. There are many options for stabilization, including external fixation, rigid internal fixation with screws and plates, percutaneous pinning, and flexible intramedullary nailing. The use of 2 flexible retrograde nails, originated at the University of Nancy, France, became the most popular technique in Europe. The aim of this study was to describe and assess a modified, single retrograde nail technique to treat fractures of the proximal part of the humerus. METHODS: We performed a retrospective monocentric study. From June 2016 to May 2019, a modified retrograde nail technique with 1 prebent nail was used for the management of 21 consecutive children with a closed displaced proximal humeral fracture. Demographic and surgical data were collected. The surgical technique is similar to the classic elastic stable intramedullary nailing, but only 1 nail is used. The average surgical time and perioperative complications were used as criteria for the feasibility of this technique. Radiographs were obtained preoperatively; at 1, 4, and 6 weeks postoperatively; and after implant removal at an average of 4.2 months postoperatively. The clinical outcomes were assessed on the basis of the shoulder range of motion documented in the medical records and by using the French edition of the QuickDASH (shortened version of the Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire) evaluation scale at the time of implant removal. RESULTS: Nineteen patients with a mean age of 12.6 years and a mean follow-up of 6 months were included in the study. The mean surgical time was 49 minutes. The single intramedullary nail technique provided a satisfactory reduction of all fractures. No perioperative complication occurred. In 1 case, partial loss of reduction was observed on the first-week control radiograph. All patients had a healed fracture, no deficits, excellent results according to the QuickDASH score, a normal range of motion, and excellent strength of the shoulder joint at the time of implant removal (at a mean of 4.2 months). CONCLUSIONS: The current study confirms the feasibility and efficacy of the single retrograde intramedullary nail technique to treat displaced proximal humeral fractures in children. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Quantitative intrinsic auto-cathodoluminescence can resolve spectral signatures of tissue-isolated collagen extracellular matrix.

By analyzing isolated collagen gel samples, we demonstrated in situ detection of spectrally deconvoluted auto-cathodoluminescence signatures of specific molecular content with precise spatial localization over a maximum field of view of 300 µm. Correlation of the secondary electron and the hyperspectral images proved ~40 nm resolution in the optical channel, obtained due to a short carrier diffusion length, suppressed by fibril dimensions and poor electrical conductivity specific to their organic composition. By correlating spectrally analyzed auto-cathodoluminescence with mass spectroscopy data, we differentiated spectral signatures of two extracellular matrices, namely human fibrin complex and rat tail collagen isolate, and uncovered differences in protein distributions of isolated extracellular matrix networks of heterogeneous populations. Furthermore, we demonstrated that cathodoluminescence can monitor the progress of a human cell-mediated remodeling process, where human collagenous matrix was deposited within a rat collagenous matrix. The revealed change of the heterogeneous biological composition was confirmed by mass spectroscopy.

Engineered acellular collagen scaffold for endogenous cell guidance, a novel approach in urethral regeneration.

UNLABELLED: The treatment of congenital malformations or injuries of the urethra using existing autologous tissues can be associated with post-operative complications. Using rat-tail collagen, we have engineered an acellular high-density collagen tube. These tubes were made of 2 layers and they could sustain greater burst pressures than the monolayered tubes. Although it remains a weak material this 2 layered tube could be sutured to the native urethra. In 20 male New Zealand white rabbits, 2cm long grafts were sutured in place after subtotal excision of the urethra. This long-term study was performed in Lausanne (Switzerland) and in Kuala Lumpur (Malaysia). No catheter was placed post-operatively. All rabbits survived the surgical implantation. The animals were evaluated at 1, 3, 6, and 9months by contrast voiding cysto-urethrography, histological examination and immunohistochemistry. Spontaneous re-population of urothelial and smooth muscle cells on all grafts was demonstrated. Cellular organization increased with time, however, 20% of both fistula and stenosis could be observed post-operatively. This off-the shelf scaffold with a promising urethral regeneration has a potential for clinical application. STATEMENT OF SIGNIFICANCE: In this study we have tissue engineered a novel cell free tubular collagen based scaffold and used it as a urethral graft in a rabbit model. The novelty of our technique is that the tube can be sutured. Testing showed better burst pressures and the grafts could then be successfully implanted after a urethral excision. This long term study demonstrated excellent biocompatibility of the 2cm graft and gradual regeneration with time, challenging the current literature. Finally, the main impact is that we describe an off-the-shelf and cost-effective product with comparable surgical outcome to the cellular grafts.

Tubular Compressed Collagen Scaffolds for Ureteral Tissue Engineering in a Flow Bioreactor System.

Ureteral replacement by tissue engineering might become necessary following tissue loss after excessive ureteral trauma, after retroperitoneal cancer, or even after failed reconstructive surgery. This need has driven innovation in the design of novel scaffolds and specific cell culture techniques for urinary tract reconstruction. In this study, compressed tubular collagen scaffolds were evaluated, addressing the physical and biological characterization of acellular and cellular collagen tubes in a new flow bioreactor system, imitating the physiological pressure, peristalsis, and flow conditions of the human ureter. Collagen tubes, containing primary human smooth muscle and urothelial cells, were evaluated regarding their change in gene and protein expression under dynamic culture conditions. A maximum intraluminal pressure of 22.43 ± 0.2 cm H2O was observed in acellular tubes, resulting in a mean wall shear stress of 4 dynes/cm(2) in the tubular constructs. Dynamic conditions directed the differentiation of both cell types into their mature forms. This was confirmed by their gene expression of smooth muscle alpha-actin, smoothelin, collagen type I and III, elastin, laminin type 1 and 5, cytokeratin 8, and uroplakin 2. In addition, smooth muscle cell alignment predominantly perpendicular to the flow direction was observed, comparable to the cell orientation in native ureteral tissue. These results revealed that coculturing human smooth muscle and urothelial cells in compressed collagen tubes under human ureteral flow-mimicking conditions could lead to cell-engineered biomaterials that might ultimately be translated into clinical applications.