Polystyrene Pocket Lithography: Sculpting Plastic with Light.

Tissue-culture-ware polystyrene is the gold standard for in vitro cell culture. While microengineering techniques can create advanced cell microenvironments in polystyrene, they require specialized equipment and reagents, which hinder their accessibility for most biological researchers. An economical and easily accessible method is developed and validated for fabricating microstructures directly in polystyrene with sizes approaching subcellular dimensions while requiring minimal processing time. The process involves deep ultraviolet irradiation through a shadow mask or ink pattern using inexpensive, handheld devices followed by selective chemical development with common reagents to generate micropatterns with depths/heights between 5 and 10 µm, which can be used to guide cell behavior. The remarkable straightforwardness of the process enables this class of microengineering techniques to be broadly accessible to diverse research communities.

Insight into the possible aetiologies of Blount's disease: a systematic review of the literature.

Blount's disease or bowed leg deformity, is a unilateral or bilateral growth deformity of the medial proximal tibia that leads to a tibial varus deformity. A distinction can be made in an early and late onset type. The disease seems to have a predisposition for certain descends. Since the first publication of Blount's disease, different hypotheses on the aetiology are proposed but no consensus exists. The objective of this study is to provide an overview of the available hypotheses on the aetiology of Blount's disease since its first description and assessment of the available level of evidence, the quality of evidence and the occurrence of bias supporting these individual hypotheses. A systematic search according to the PRISMA statement was conducted using PubMed, MEDLINE, EMBASE and the Cochrane Library using a broad combination of terminology to ascertain a complete selection. Proper MESH search criteria were formulated and the bibliographic search was limited to English and Dutch language articles. Articles with no mention of aetiology or a disease related to Blount's were excluded. Level of evidence and types of bias were assessed. Thirty-two articles that discuss the aetiology of Blount's disease were selected. A variety of hypotheses was postulated in these articles with most research in the field of increased mechanical pressure (obesity, early walking age) and race (descend). Blount's disease most likely has a multifactorial origin with influence of genetic and racial predisposition, increased mechanical pressure on the growth plate as a consequence of obesity or early walking age and possibly also nutrition. However, the exact aetiology remains unclear, the probable explanation is that multifactorial factors are all contributing to the development of Blount's disease. Histological research has shown that a disorganization of bone and cartilage structures on the medial side of the proximal tibial physis is present in patients with Blount's disease. Based on the available evidence on the aetiology of Blount's disease, we conclude that it is multifactorial. Most papers focus only on one hypotheses of Blount's disease occurrence and all are characterized as low level of evidence. There seems to be a preference for certain descends. Further research on especially genetic predisposition is needed to provide more insight in this factor of Blount's disease.

Modeling the Mechanical Parameters of Glaucoma.

Glaucoma is a major eye disease characterized by a progressive loss of retinal ganglion cells (RGCs). Biomechanical forces as a result of hydrostatic pressure and strain play a role in this disease. Decreasing intraocular pressure is the only available therapy so far, but is not always effective and does not prevent blindness in many cases. There is a need for drugs that protect RGCs from dying in glaucoma; to develop these, we need valid glaucoma and drug screening models. Since in vivo models are unsuitable for screening purposes, we focus on in vitro and ex vivo models in this review. Many groups have studied pressure and strain model systems to mimic glaucoma, to investigate the molecular and cellular events leading to mechanically induced RGC death. Therefore, the focus of this review is on the different mechanical model systems used to mimic the biomechanical forces in glaucoma. Most models use either cell or tissue strain, or fluid- or gas-controlled hydrostatic pressure application and apply it to the relevant cell types such as trabecular meshwork cells, optic nerve head astrocytes, and RGCs, but also to entire eyes. New model systems are warranted to study concepts and test experimental compounds for the development of new drugs to protect vision in glaucoma patients. Impact Statement The outcome of currently developed models to investigate mechanically induced retinal ganglion cell death by applying different mechanical strains varies widely. This suggests that a robust glaucoma model has not been developed yet. However, a comprehensive overview of current developments is not available. In this review, we have therefore assessed what has been done before and summarized the available knowledge in the field, which can be used to develop improved models for glaucoma research.

Identification of topographical architectures supporting the phenotype of rat tenocytes.

Tenocytes, the main cell type of the tendon, require mechanical stimuli for their proper function. When the tenocyte environment changes due to tissue damage or by transferring tenocytes from their native environment into cell culture, the signals from the tenocyte niche are lost, leading towards a decline of phenotypic markers. It is known that micro-topographies can influence cell fate by the physical cues they provide. To identify the optimal topography-induced biomechanical niche in vitro, we seeded tenocytes on the TopoChip, a micro-topographical screening platform, and measured expression of the tendon transcription factor Scleraxis. Through machine learning algorithms, we associated elevated Scleraxis levels with topological design parameters. Fabricating micro-topographies with optimal surface characteristics on larger surfaces allowed finding an improved expression of multiple tenogenic markers. However, long-term confluent culture conditions coincided with osteogenic marker expression and the loss of morphological characteristics. In contrast, passaging tenocytes which migrated from the tendon directly on the topography resulted in prolonged elongated morphology and elevated Scleraxis levels. This research provides new insights into how micro-topographies influence tenocyte cell fate, and supports the notion that micro-topographical design can be implemented in a new generation of tissue culture platforms for supporting the phenotype of tenocytes. STATEMENT OF SIGNIFICANCE: The challenge in controlling in vitro cell behavior lies in controlling the complex culture environment. Here, we present for the first time the use of micro-topographies as a biomechanical niche to support the phenotype of tenocytes. For this, we applied the TopoChip platform, a screening tool with 2176 unique micro-topographies for identifying feature characteristics associated with elevated Scleraxis expression, a tendon related marker. Large area fabrication of micro-topographies with favorable characteristics allowed us to find a beneficial influence on other tenogenic markers as well. Furthermore, passaging cells is more beneficial for Scleraxis marker expression and tenocyte morphology compared to confluent conditions. This study presents important insights for the understanding of tenocyte behavior in vitro, a necessary step towards tendon engineering.