The changing integrin expression and a role for integrin beta 8 in the chondrogenic differentiation of mesenchymal stem cells

Many cartilage tissue engineering approaches aim to differentiate human mesenchymal stem cells (hMSCs) into chondrocytes and develop cartilage in vitro by targeting cell-matrix interactions. We sought to better inform the design of cartilage tissue engineering scaffolds by understanding how integrin expression changes during chondrogenic differentiation. In three models of in vitro chondrogenesis, we studied the temporal change of cartilage phenotype markers and integrin subunits during the differentiation of hMSCs. We found that transcript expression of most subunits was conserved across the chondrogenesis models, but was significantly affected by the time-course of differentiation. In particular, ITGB8 was up-regulated and its importance in chondrogenesis was further established by a knockdown of integrin β8, which resulted in a non-hyaline cartilage phenotype, with no COL2A1 expression detected. In conclusion, we performed a systematic study of the temporal changes of integrin expression during chondrogenic differentiation in multiple chondrogenesis models, and revealed a role for integrin β8 in chondrogenesis. This work enhances our understanding of the changing adhesion requirements of hMSCs during chondrogenic differentiation and underlines the importance of integrins in establishing a cartilage phenotype

Changes in embryonic stem cell colony morphology and early differentiation markers driven by colloidal crystal topographical cues

The use of materials properties to guide cell behaviour is an attractive option for regenerative medicine, where controlling stem cell behaviour is important for the establishment of a functioning cell population. A wide range of materials properties have been shown to influence many types of cells but little is known about the effects of topography on embryonic stem cells (ESCs). In order to advance this knowledge, we synthesised and characterised substrates formed of silica colloidal crystal (SCC) microspheres to present highly ordered and reproducible topographical features from 120-600 nm in diameter. We found that, compared to cells cultured on flat glass, cells cultured on the SCC substrates retained transcription of stem cell (Dppa5a, Nanog, and Pou5f1) and endoderm (Afp, Gata4, Sox17, and Foxa2) markers more similar to undifferentiated ESCs, suggesting the substrates are restricting differentiation, particularly towards the endoderm lineage. Additionally, five days after seeding, we observed strikingly different colony morphology, with cells on the SCC substrates growing in spherical colonies approximately ten cells thick, while cells on glass were growing in flat monolayers. Colonies on the SCC substrates developed a central pit, which was never observed in cells cultured on glass, and expressed proteins related to epithelialisation. Together, these data demonstrate the potential of using topographical cues to control stem cell behaviour in vitro

Cell aggregation enhances bone formation by human mesenchymal stromal cells

he amount of bone generated using current tissue engineering approaches is insufficient for many clinical applications. Previous in vitro studies suggest that culturing cells as 3D aggregates can enhance their osteogenic potential, but the effect on bone formation in vivo is unknown. Here, we use agarose wells to generate uniformly sized mesenchymal stromal cell (MSC) aggregates. When combined with calcium phosphate ceramic particles and a gel prepared from human platelet-rich plasma, we generated a tissue engineered construct which significantly improved in vivo bone forming capacity as compared to the conventional system of using single cells seeded directly on the ceramic surface. Histology demonstrated the reproducibility of this system, which was tested using cells from four different donors. In vitro studies established that MSC aggregation results in an up-regulation of osteogenic transcripts. And finally, the in vivo performance of the constructs was significantly diminished when unaggregated cells were used, indicating that cell aggregation is a potent trigger of in vivo bone formation by MSCs. Cell aggregation could thus be used to improve bone tissue engineering strategies

Corrigendum to “Future directions in managing aniridia-associated keratopathy” [Surv Ophthalmol 68 (2023) 940–956, (S0039625723000668), (10.1016/j.survophthal.2023.04.003)]

\ua9 2024 The Authors. The authors regret (changes marked in bold): Arianne J.H. van Velthoven a b, Tor P. Utheim M.D. Dr. c d, Maria Notara Dr. e, Dominique Bremond-Gignac M.D. Dr. f g, Francisco C. Figueiredo M.D. Dr. h i, Heli Skottman Dr. j, Daniel Aberdam Dr. g, Julie T. Daniels Dr. k, Giulio Ferrari M.D. Dr. l m, Christina Grupcheva M.D. Dr. n, Carina Koppen M.D. Dr. \ub0, Mohit Parekh Dr. p, Thomas Ritter Dr. q, Vito Romano Dr. r, Stefano Ferrari Dr. s 1, Claus Cursiefen M.D. Dr. e t 1, Neil Lagali Dr. u 1, Vanessa L.S. LaPointe Dr. a 1, Mor M. Dickman M.D. Dr. a b 1 a MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands b University Eye Clinic Maastricht, Maastricht University Medical Center+, Maastricht, the Netherlands c Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway d Department of Ophthalmology, Oslo University Hospital, Oslo, Norway e Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, Cologne, Germany f Ophthalmology Department, University Hospital Necker-Enfants Malades, APHP, Paris Cit\ue9 University, Paris, France g Centre de Recherche des Cordeliers, Sorbonne Paris Cit\ue9 University, Paris, France h Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK i Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK j Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland k UCL Institute of Ophthalmology, London, UK l IRCCS San Raffaele Scientific Institute, Division of Neuroscience, Cornea and Ocular Surface Disease Unit, Eye Repair Lab, Milan, Italy m Vita-Salute San Raffaele University, Dept. Of Ophthalmology, Milan, Italy n Department of Ophthalmology and Visual Sciences, Medical University of Varna, Varna, Bulgaria o Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium p Schepens Eye Research Institute, Harvard Medical School, Boston, MA, USA q Regenerative Medicine Institute, University of Galway, Galway, Ireland r Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, Ophthalmology Clinic, University of Brescia, Brescia, Italy s Fondazione Banca degli Occhi del Veneto, Venice, Italy t Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany u Division of Ophthalmology, Department of Biomedical and Clinical Sciences, Link\uf6ping University, Link\uf6ping, Sweden The authors would like to apologise for any inconvenience cause

Lasers Med Sci

Cell oxygenation and nutrition are crucial for the viability of tissue-engineered constructs, and different alternatives are currently being developed to achieve an adequate vascularisation of the engineered tissue. One of the alternatives is the generation of channel-like patterns in a bioconstruct. Here, the formation of full-formed channels inside hydrogels by laser-induced cavitation was investigated. A near-infrared, femtosecond laser beam focused with a high numerical aperture was employed to obtain intra-volume modifications of a block of gelatine hydrogel. Characterisation of the laser-processed gelatine was carried out by optical microscopy and epifluorescence microscopy right after and 24 h after the laser process. Rheology analyses on the unprocessed gelatine blocks were conducted to better understand the cavitation mechanism taking place during the intense laser interaction. Different cavitation patterns were observed at varying dose values by changing the repetition rate and the overlap between successive pulses while keeping the laser fluence and the number of passes fixed. This way, cavitation bubble features and behaviour can be controlled to optimise the formation of intra-volume channels in the gelatine volume. Results showed that the generation of fully formed channels was linked to the formation of large non-spherical cavitation bubbles during the laser interaction at high dose and low repetition rates. In conclusion, the formation of fully formed channels was made possible with a near-infrared, femtosecond laser beam strongly focused inside gelatine hydrogel blocks through laser-induced cavitation at high dose and low repetition rates

Vascular bioengineering of scaffolds derived from human discarded transplant kidneys using human pluripotent stem cell-derived endothelium

The bioengineering of a replacement kidney has been proposed as an approach to address the growing shortage of donor kidneys for the treatment of chronic kidney disease. One approach being investigated is the recellularization of kidney scaffolds. In this study, we present several key advances toward successful re-endothelialization of whole kidney matrix scaffolds from both rodents and humans. Based on the presence of preserved glycosoaminoglycans within the decelullarized kidney scaffold, we show improved localization of delivered endothelial cells after preloading of the vascular matrix with vascular endothelial growth factor and angiopoietin 1. Using a novel simultaneous arteriovenous delivery system, we report the complete re-endothelialization of the kidney vasculature, including the glomerular and peritubular capillaries, using human inducible pluripotent stem cell -derived endothelial cells. Using this source of endothelial cells, it was possible to generate sufficient endothelial cells to recellularize an entire human kidney scaffold, achieving efficient cell delivery, adherence, and endothelial cell proliferation and survival. Moreover, human re-endothelialized scaffold could, in contrast to the non-re-endothelialized human scaffold, be fully perfused with whole blood. These major advances move the field closer to a human bioengineered kidney