Chondrogenesis of mesenchymal stem cells (MSCs) is typically induced when they are condensed into a single aggregate and exposed to transforming growth factor-β (TGF-β). Hypoxia, like aggregation and TGF-β delivery, may be crucial for complete chondrogenesis. However, the pellet dimensions and associated self-induced oxygen gradients of current chondrogenic methods may limit the effectiveness of in vitro differentiation and subsequent therapeutic uses. Here we describe the use of embryoid body-forming technology to produce microscopic aggregates of human bone marrow MSCs (BM-MSCs) for chondrogenesis. The use of micropellets reduces the formation of gradients within the aggregates, resulting in a more homogeneous and controlled microenvironment. These micropellet cultures (~170 cells/micropellet) as well as conventional pellet cultures (~2 × 10 ⁵ cells/pellet) were chondrogenically induced under 20% and 2% oxygen environments for 14 days. Compared to conventional pellets under both environments, micropellets differentiated under 2% O ₂ showed significantly increased sulfated glycosaminoglycan (sGAG) production and more homogeneous distribution of proteoglycans and collagen II. Aggrecan and collagen II gene expressions were increased in pellet cultures differentiated under 2% O ₂ relative to 20% O ₂ pellets but 2% O ₂ micropellets showed even greater increases in these genes, as well as increased SOX9. These results suggest a more advanced stage of chondrogenesis in the micropellets accompanied by more homogeneous differentiation. Thus, we present a new method for enhancing MSC chondrogenesis that reveals a unique relationship between oxygen tension and aggregate size. The inherent advantages of chondrogenic micropellets over a single macroscopic aggregate should allow for easy integration with a variety of cartilage engineering strategies.

Endorepellin, the C-terminal module of perlecan, negatively regulates angiogenesis counter to its proangiogenic parental molecule. Endorepellin (the C-terminal domain V of perlecan) binds the α2β1 integrin on endothelial cells and triggers a signaling cascade that leads to disruption of the actin cytoskeleton. Here, we show that both perlecan and endorepellin bind directly and with high affinity to both VEGF receptors 1 and 2, in a region that differs from VEGFA-binding site. In both human and porcine endothelial cells, this interaction evokes a physical down-regulation of both the α2β1 integrin and VEGFR2, with concurrent activation of the tyrosine phosphatase SHP-1 and downstream attenuation of VEGFA transcription. We demonstrate that endorepellin requires both the α2β1 integrin and VEGFR2 for its angiostatic activity. Endothelial cells that express α2β1 integrin but lack VEGFR2, do not respond to endorepellin treatment. Thus, we provide a new paradigm for the activity of an antiangiogenic protein and mechanistically explain the specificity of endorepellin for endothelial cells, the only cells that simultaneously express both receptors. We hypothesize that a mechanism such as dual receptor antagonism could operate for other angiostatic fragments.

Shear stresses are known to influence the morphology, and even the fate, of many cell types, including endothelial, smooth muscle, and osteoblast cells. This paper describes a novel shear device for the study of cell mechanics. Unlike all other published shear devices, such as parallel-plate flow chambers, where a single shear stress is evaluated for a single input flow rate, the described device enables the simultaneous evaluation of 10 different shear stresses ranging over two orders of magnitude (0.7–130 dynes cm⁻², 0.07–13 Pa). Human umblical vein endothelial cells (HUVECs) were exposed to the shear stress profiles provided by the device over a 20 h perfusion period, and the secretion level of von Willebrand factor (vWF) was investigated. Confirming previous studies, increasing shear resulted in increased vWF secretion. Furthermore, changes in cell morphology, including cell and nuclear size (area) and perimeter with shear, were analysed. HUVECs under shear stresses ranging from 1–3 dynes cm⁻² (0.1–0.3 Pa) showed similar vWF content, cell and nuclear size and perimeter to static cultures, while cells under shear stresses above 5 dynes cm⁻² (0.5 Pa) showed significantly higher vWF secretion and were at least 30% smaller in cell size. We also note that cells exposed to perfusion rates resulting in a shear stress of 0.7 dynes cm⁻² (0.07 Pa) showed significantly lower levels of vWF and were 35% smaller in size than those under static conditions. Overall, the results confirm the significant utility of this device to rapidly screen cellular responses to simultaneously imposed physiologically relevant ranges of shear stress.

Early-career researchers (ECRs) make up a large portion of the academic workforce and their experiences often reflect the wider culture of the research system. Here we surveyed 658 ECRs working in Australia to better understand the needs and challenges faced by this community. Although most respondents indicated a ‘love of science’, many also expressed an intention to leave their research position. The responses highlight how job insecurity, workplace culture, mentorship and ‘questionable research practices’ are impacting the job satisfaction of ECRs and potentially compromising science in Australia. We also make recommendations for addressing some of these concerns.

Treatment following early diagnosis of Prostate cancer (PCa) is increasingly successful, whilst the treatment of advanced and metastatic PCa remains challenging. A major limitation in the development of new therapies is the prediction of drug efficacy using in vitro models. Classic in vitro 2-dimensional (2D) cell monolayer cultures are hypersensitive to anti-cancer drugs. As a result, there has been a surge in the development of platforms that enable three dimensional (3D) cultures thought to better replicate natural physiology and better predict drug efficacy. A deficiency associated with most 3D culture systems is that their complexity reduces the number of replicates and combination therapies that can be feasibly evaluated. Herein, we describe the use of a microwell platform that utilises a nylon mesh to retain 3D micro-tumours in discrete microwells; termed the Microwell-mesh. The Microwell-mesh enables the manufacture of ~150 micro-tumours per well in a 48-well plate, and response to anti-tumour drugs can be readily quantified. Our results demonstrate that 3D micro-tumours, unlike 2D monolayers, are not hypersensitive to Docetaxel or Abiraterone Acetate, providing a superior platform for the evaluation of sequential drug treatment. In summary, the Microwell-mesh provides an efficient 3D micro-tumour platform for single and sequential drug screening.