Hyaluronan improves photoreceptor differentiation and maturation in human retinal organoids.

Human stem cell-derived organoids enable both disease modeling and serve as a source of cells for transplantation. Human retinal organoids are particularly important as a source of human photoreceptors; however, the long differentiation period required and lack of vascularization in the organoid often results in a necrotic core and death of inner retinal cells before photoreceptors are fully mature. Manipulating the in vitro environment of differentiating retinal organoids through the incorporation of extracellular matrix components could influence retinal development. We investigated the addition of hyaluronan (HA), a component of the interphotoreceptor matrix, as an additive to promote long-term organoid survival and enhance retinal maturation. HA treatment had a significant reduction in the proportion of proliferating (Ki67+) cells and increase in the proportion of photoreceptors (CRX+), suggesting that HA accelerated photoreceptor commitment in vitro. HA significantly upregulated genes specific to photoreceptor maturation and outer segment development. Interestingly, prolonged HA-treatment significantly decreased the length of the brush border layer compared to those in control retinal organoids, where the photoreceptor outer segments reside; however, HA-treated organoids also had more mature outer segments with organized discs structures, as revealed by transmission electron microscopy. The brush border layer length was inversely proportional to the molar mass and viscosity of the hyaluronan added. This is the first study to investigate the role of exogenous HA, viscosity, and polymer molar mass on photoreceptor maturation, emphasizing the importance of material properties on organoid culture. STATEMENT OF SIGNIFICANCE: Retinal organoids are a powerful tool to study retinal development in vitro, though like many other organoid systems, can be highly variable. In this work, Shoichet and colleagues investigated the use of hyaluronan (HA), a native component of the interphotoreceptor matrix, to improve photoreceptor maturation in developing human retinal organoids. HA promoted human photoreceptor differentiation leading to mature outer segments with disc formation and more uniform and healthy retinal organoids. These findings highlight the importance of adding components native to the developing retina to generate more physiologically relevant photoreceptors for cell therapy and in vitro models to drive drug discovery and uncover novel disease mechanisms.

Transplanted human photoreceptors transfer cytoplasmic material but not to the recipient mouse retina.

BACKGROUND: The discovery of material transfer between transplanted and host mouse photoreceptors has expanded the possibilities for utilizing transplanted photoreceptors as potential vehicles for delivering therapeutic cargo. However, previous research has not directly explored the capacity for human photoreceptors to engage in material transfer, as human photoreceptor transplantation has primarily been investigated in rodent models of late-stage retinal disease, which lack host photoreceptors. METHODS: In this study, we transplanted human stem-cell derived photoreceptors purified from human retinal organoids at different ontological ages (weeks 10, 14, or 20) into mouse models with intact photoreceptors and assessed transfer of human proteins and organelles to mouse photoreceptors. RESULTS: Unexpectedly, regardless of donor age or mouse recipient background, human photoreceptors did not transfer material in the mouse retina, though a rare subset of donor cells (< 5%) integrated into the mouse photoreceptor cell layer. To investigate the possibility that a species barrier impeded transfer, we used a flow cytometric assay to examine material transfer in vitro. Interestingly, dissociated human photoreceptors transferred fluorescent protein with each other in vitro, yet no transfer was detected in co-cultures of human and mouse photoreceptors, suggesting that material transfer is species specific. CONCLUSIONS: While xenograft models are not a tractable system to study material transfer of human photoreceptors, these findings demonstrate that human retinal organoid-derived photoreceptors are competent donors for material transfer and thus may be useful to treat retinal degenerative disease.

Periodontal status is associated with oral function in community-dwelling older adults, independent of dentition status.

OBJECTIVE: To determine whether periodontal status is associated with oral function, including masticatory performance and occlusal force, among community-dwelling older adults. BACKGROUND: Although a potential association between periodontal status and oral function has been reported, variations in the root surface area (RSA) of each tooth have not been considered. METHODS: We used data from a population-based study involving community-dwelling older adults. The RSA with periodontal ligament (RSA-PL), which quantifies the RSA attached to the periodontal ligament and alveolar bone, was calculated based on full-mouth periodontal examination. Masticatory performance was assessed using spectrophotometric measurement of the color (a* value) of color-changing chewing gum. The bilateral maximal occlusal force (MOF) was measured using a pressure-sensitive sheet and dedicated software. The associations of the RSA-PL, a quantitative marker of periodontal tissue support, with the a* value and MOF were assessed using linear regression models. RESULTS: The analyses included data from 250 adults [60.8% women; age, mean (standard deviation) 82.5 (5.0) years]. On average, the study participants had an RSA-PL of 26.3 cm2 , a* value of 25.0, and an MOF value of 555.1 N. After adjustments for potential confounders, including dentition status, age, sex, dental visit regularity, smoking status, physical activity level, depressive symptoms, a history of stroke or diabetes mellitus, and body mass index, the RSA-PL was found to be associated with the a* value [coefficient (per 1 cm2 increase): 0.16, 95% confidence interval (CI) 0.10-0.22)] and MOF (coefficient: 9.2, 95% CI 5.3-13.1). CONCLUSION: This study demonstrated that greater amounts of remaining tooth-supporting structures, indicated by higher RSA-PL values, were associated with better masticatory performance and a higher occlusal force among community-dwelling older adults.

[Anesthetic management of cesarean section in a patient with pulmonary embolism due to protein S deficiency diagnosed postoperatively].

A 27-year-old pregnant woman with pulmonary embolism was scheduled for cesarean section. She received anticoagulant therapy with continuous infusion of heparin and prophylactic placement of an inferior vena cava (IVC) filter. Heparin was discontinued 7 hours before operation. Spinal anesthesia using hyperbaric bupivacaine 12 mg was performed and the operation was completed uneventfully. She was given a diagnosis of protein S deficiency after discharge. Preoperative anticoagulant therapy and placement of IVC filter may be effective in preventing new pulmonary embolism.