Research perspectives-Pipelines to human tendon transcriptomics.

Tendon transcriptomics is a rapidly growing field in musculoskeletal biology. The ultimate aim of many current tendon transcriptomic studies is characterization of in vitro, ex vivo, or in vivo, healthy, and diseased tendon microenvironments to identify the underlying pathways driving human tendon pathology. The transcriptome interfaces between genomic, proteomic, and metabolomic signatures of the tendon cellular niche and the response of this niche to stimuli. Some of the greatest bottlenecks in tendon transcriptomics relate to the availability and quality of human tendon tissue, hence animal tissues are frequently used even though human tissue is most translationally relevant. Here, we review the variability associated with human donor and procurement factors, such as whether the tendon is cadaveric or a clinical remnant, and how these variables affect the quality and relevance of the transcriptomes obtained. Moreover, age, sex, and health demographic variables impact the human tendon transcriptome. Tendons present tissue-specific challenges for cell, nuclei, and RNA extraction that include a dense extracellular matrix, low cellularity, and therefore low RNA yield of variable quality. Consideration of these factors is particularly important for single-cell and single-nuclei resolution transcriptomics due to the necessity for unbiased and representative cell or nuclei populations. Different cell, nuclei, and RNA extraction methods, library preparation, and quality control methods are used by the tendon research community and attention should be paid to these when designing and reporting studies. We discuss the different components and challenges of human tendon transcriptomics, and propose pipelines, quality control, and reporting guidelines for future work in the field.

Tendon and multiomics: advantages, advances, and opportunities.

Tendons heal by fibrosis, which hinders function and increases re-injury risk. Yet the biology that leads to degeneration and regeneration of tendons is not completely understood. Improved understanding of the metabolic nuances that cause diverse outcomes in tendinopathies is required to solve these problems. 'Omics methods are increasingly used to characterize phenotypes in tissues. Multiomics integrates 'omic datasets to identify coherent relationships and provide insight into differences in molecular and metabolic pathways between anatomic locations, and disease stages. This work reviews the current literature pertaining to multiomics in tendon and the potential of these platforms to improve tendon regeneration. We assessed the literature and identified areas where 'omics platforms contribute to the field: (1) Tendon biology where their hierarchical complexity and demographic factors are studied. (2) Tendon degeneration and healing, where comparisons across tendon pathologies are analyzed. (3) The in vitro engineered tendon phenotype, where we compare the engineered phenotype to relevant native tissues. (4) Finally, we review regenerative and therapeutic approaches. We identified gaps in current knowledge and opportunities for future study: (1) The need to increase the diversity of human subjects and cell sources. (2) Opportunities to improve understanding of tendon heterogeneity. (3) The need to use these improvements to inform new engineered and regenerative therapeutic approaches. (4) The need to increase understanding of the development of tendon pathology. Together, the expanding use of various 'omics platforms and data analysis resulting from these platforms could substantially contribute to major advances in the tendon tissue engineering and regenerative medicine field.

Descripción anatómica de la inserción de la raíz del cuerno posterior del menisco medial de la rodilla humana / Anatomical Study of the Posterior Root of Medial Meniscus in Human Knee

Introducción El conocimiento anatómico de la huella de la raíz del cuerno posterior del menisco medial (CPMM) de la rodilla es fundamental en la planeación de la reinserción meniscal. El objetivo del estudio es describir la ubicación la huella de la raíz del cuerno posterior del menisco medial y definir su relación topográfica con los ligamentos cruzados en la rodilla humana en cadáveres. Materiales & Métodos Fueron estudiadas 10 rodillas de cadáveres humanos. Estas muestras tenían los ligamentos cruzados y los meniscos intactos, sin evidencia de trauma en la meseta tibial. Se identificaron y mapearon las raíces posteriores con base en la relación topográfica de las huellas en los platillos tibiales. Se realizaron medidas del tamaño de los platillos tibiales, la raíz y su distancia a los ligamentos cruzados. Se tomaron tomografías a cada espécimen para evaluar el centro de la huella de la raíz. Se determinó la posición calculando el porcentaje de la distancia del borde medial de la meseta tibial al centro de la inserción. Resultados La raíz posterior del menisco medial tiene una medida antero-posterior de 8.3mm (DE: 2.7) y medio-lateral de 4.3mm (DE: 1.5). Se encuentra a 6.9mm (DE: 2.3) de la inserción tibial del ligamento cruzado posterior y a 11.4mm (DE: 1.06) de la inserción tibial del ligamento cruzado anterior. Discusión La huella de la inserción del CPMM tiene forma ovalada con mayor diámetro anteroposterior, que guarda una relación estrecha con las estructuras intraarticulares de la rodilla, siendo un punto de referencia para procedimientos de reinserción precisos. Nivel de Evidencia IV

Background The anatomical knowledge of the footprint of the root of the posterior horn of the medial meniscus (PRMM) of the knee is essential in planning the meniscal reinsertion. The aim of this study was to describe the footprint of the Posterior Root of Medial Meniscus and define the topographical relationship with Cruciate Ligaments in the human knee. Methods Ten human cadaveric knees were studied. These samples had intact cruciate ligaments and meniscus with no evidence of trauma on the tibial plateau. The Posterior Horn of the Medial Meniscus was removed from the Posterior Root. We identified and mapped the Posterior Root based on the topographical relationship with its tibial footprint. We performed measurements of the tibial plateaús size, the root and its distance to the cruciate ligaments. Each knee had a CT scan and 3D reconstruction with a metalic tool that served as reference at the center of the root. Results The Posterior Root of Medial Meniscus has a higher anteroposterior foot print 8.3mm (SD2.7) than medio-lateral 4.3mm (SD 1.5). Is located 6.9mm (SD 2.3) from the tibial insertion of Posterior Cruciate Ligament and 11.4mm (SD 1.06) from the tibial insertion of Anterior Cruciate Ligament. Discussion This anatomical study provides new knowledge and information concerning the foot print of the root of posterior horn of the medial meniscus in the human knee. It could be a starting point to help surgeons to perform more anatomical procedures. Evidence Level IV

Tridimensional alginate disks of tunable topologies for mammalian cell encapsulation.

We have developed a protocol to produce three-dimensional matrices based on alginate hydrogels for mammalian cell encapsulation. Based on the gelation properties of this polysaccharide, we implemented a calcium ion-based diffusion method where the designed hydrogels can be obtained with well-defined mechanical properties and replicable 3D topologies. The developed protocol can be extended to different types of alginates and an ample range of concentrations. This makes it very attractive for various biomedical applications where strict control over structure-function relationships is desirable.