Biology subjects

Amer, M. H.

Publications and source records attributed to Amer, M. H..

4 recordsLinked to original sources

bioRxiv2025

A Design-of-Experiments Strategy for Engineering 3D Topographical Features in Osteosarcoma Modelling

Osteosarcoma is a highly aggressive bone cancer with poor patient outcomes, partly due to the limited predictive power of current preclinical models. Conventional two-dimensional (2D) cultures fail to recapitulate physiologically relevant cell-matrix interactions, while animal models suffer from inter-species variability. To investigate how extracellular matrix (ECM) topographical features influence osteosarcoma behaviour, polylactic acid-based microparticles were engineered with bone-mimetic stiffness and defined surface topographies, guided by a Design-of-Experiments (DoE) approach. This enabled systematic variation of microparticle architecture (8-63 {micro}m diameter; 2-13 {micro}m dimple size) for studying the impact of surface topography on osteosarcoma cell behaviour in 3D culture, with doxorubicin treatment as a functional test to evaluate the effect of 3D topographical cues on chemotherapy sensitivity. Topography modulated cell-microparticle aggregation dynamics. At 96 hours post-seeding, MG-63 cells displayed significantly reduced metabolic activity on all 3D microparticle designs, with heterogeneously dimpled-topography cultures displaying significantly lower DNA content than conventional 2D cultures. In U2OS cells, metabolic activity was significantly lower on smooth microparticles compared to dimpled designs, with all 3D cultures showing significantly lower DNA content versus 2D. Response to doxorubicin was more strongly influenced by culture dimensionality than surface topography, underscoring the importance of 3D context. Significant metabolic differences between 3D and 2D cultures were observed, including the enrichment of amino acid related pathways and downregulation of ferroptosis signatures in 3D microparticle cultures. Topography displayed subtler effects on lipid and nucleotide metabolism. This study highlights how topographically-patterned 3D substrates can shape osteosarcoma cell behaviour and drug response for disease modelling applications. Our DoE-guided platform enables systematic investigation for dissecting how ECM-inspired physical cues influence osteosarcoma progression and therapeutic resistance. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=99 SRC="FIGDIR/small/674028v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@42352aorg.highwire.dtl.DTLVardef@b066e4org.highwire.dtl.DTLVardef@13322e3org.highwire.dtl.DTLVardef@377d4a_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

A Modular Bioinstructive Platform for Additive-Free, Topography-Driven Stem Cell Differentiation and Patterning

Recreating 3D bone formation in vitro without biochemical inducers remains a longstanding challenge in preclinical testing. We present a scalable, bioinstructive platform based on polylactic acid microparticles with controlled dimpled surface features that direct mesenchymal stem cell differentiation through endogenous topography-mediated mechanotransduction, establishing a mechanistically validated, additive-free platform. These 3D topographical cues drive cytoskeletal reorganisation and induce osteogenesis via canonical Hedgehog signalling. RNA-Seq revealed early significant upregulation of cytoskeletal components and osteochondral transcription factors, including runt-related transcription factor 2 (RUNX2) and SRY-box transcription factor 9 (SOX9), followed by activation of the insulin growth factor-II pathway and osteogenic commitment. To demonstrate translational potential, two-photon polymerisation lithography was employed to engineer precisely-patterned 3D topographies, inducing graded GLI1 expression without added soluble cues. This establishes a modular, versatile platform for stem cell engineering, offering a topography-driven, non-genetic analogue to mechanogenetics with broad utility for regenerative medicine and human-relevant development of bone models. O_FIG O_LINKSMALLFIG WIDTH=162 HEIGHT=200 SRC="FIGDIR/small/664383v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@1b06d7dorg.highwire.dtl.DTLVardef@1e464e1org.highwire.dtl.DTLVardef@19b1299org.highwire.dtl.DTLVardef@1e21f89_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

bioengineering↗

bioRxiv2023

Towards Modular Engineering of Cell Signalling: Topographically-Textured Microparticles Induce Osteogenesis via Activation of Canonical Hedgehog Signalling

Polymer microparticles possess great potential as functional building blocks for advanced bottom-up engineering of complex tissues. Tailoring the three-dimensional architectural features of culture substrates has been shown to induce osteogenesis in mesenchymal stem cells in vitro, but the molecular mechanisms underpinning this remain unclear. This study proposes a mechanism linking the activation of Hedgehog signalling to the osteoinductive effect of surface-engineered, topographically-textured polymeric microparticles. In this study, mesenchymal progenitor C3H10T1/2 cells were cultured on smooth and dimpled poly(D,L-lactide) microparticles to assess differences in viability, cellular morphology, proliferation, and expression of a range of Hedgehog signalling components and osteogenesis-related genes. Dimpled microparticles induced osteogenesis and activated the Hedgehog signalling pathway relative to smooth microparticles and 2D-cultured controls without the addition of exogenous biochemical factors. We observed upregulation of the osteogenesis markers Runt-related transcription factor2 (Runx2) and bone gamma-carboxyglutamate protein 2 (Bglap2), as well as the Hedgehog signalling components, glioma associated oncogene homolog 1 (Gli1), Patched1 (Ptch1), and Smoothened (Smo). Treatment with the Smo antagonist KAAD-cyclopamine confirmed the involvement of Smo in Gli1 target gene activation, with a significant reduction in the expression of Gli1, Runx2 and Bglap2 (p[≤]0.001) following KAAD-cyclopamine treatment. Overall, our study demonstrates the role of the topographical microenvironment in the modulation of Hedgehog signalling, highlighting the potential for tailoring substrate topographical design to offer cell-instructive 3D microenvironments. Topographically-textured microparticles allow the modulation of Hedgehog signalling in vitro without adding exogenous biochemical agonists, thereby eliminating potential confounding artefacts in high-throughput drug screening applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=134 HEIGHT=200 SRC="FIGDIR/small/549481v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@cdeb88org.highwire.dtl.DTLVardef@1224098org.highwire.dtl.DTLVardef@1bee1b1org.highwire.dtl.DTLVardef@d34708_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2020

Designing Topographically Textured Microparticles For Induction and Modulation of Osteogenesis in Mesenchymal Stem Cell Engineering

Mesenchymal stem cells have been the focus of intense research in bone development and regeneration. We demonstrate the potential of microparticles as modulating moieties of osteogenic response by utilizing their architectural features. Topographically textured microparticles of varying microscale features were produced by exploiting phase-separation of a readily-soluble sacrificial component from polylactic acid. The influence of varying topographical features on primary human mesenchymal stem cell attachment, proliferation and markers of osteogenesis was investigated. In the absence of osteoinductive supplements, cells cultured on textured microparticles exhibited notably increased expression of osteogenic markers relative to conventional smooth microparticles. They also exhibited varying morphological, attachment and proliferation responses. Significantly altered gene expression and metabolic profiles were observed, with varying histological characteristics in vivo. This study highlights how tailoring topographical design offers cell-instructive 3D microenvironments which allow manipulation of stem cell fate by eliciting the desired downstream response without use of exogenous osteoinductive factors.

bioengineering↗