An integrated microfluidic device for stem cell differentiation based on cell-imprinted substrate designed for cartilage regeneration in a rabbit model

Directed Differentiation of Adipose-Derived Stem Cells Using Imprinted Cell-Like Topographies as a Growth Factor-Free Approach

The influence of surface topography on stem cell behavior and differentiation has garnered significant attention in regenerative medicine and tissue engineering. The cell-imprinting method has been introduced as a promising approach to mimic the geometry and topography of cells. The cell-imprinted substrates are designed to replicate the topographies and dimensions of target cells, enabling tailored interactions that promote the differentiation of stem cells towards desired specialized cell types. In fact, by replicating the size and shape of cells, biomimetic substrates provide physical cues that profoundly impact stem cell differentiation. These cues play a pivotal role in directing cell morphology, cytoskeletal organization, and gene expression, ultimately influencing lineage commitment. The biomimetic substrates' ability to emulate the native cellular microenvironment supports the creation of platforms capable of steering stem cell fate with high precision. This review discusses the role of mechanical factors that impact stem cell fate. It also provides an overview of the design and fabrication principles of cell-imprinted substrates. Furthermore, the paper delves into the use of cell-imprinted polydimethylsiloxane (PDMS) substrates to direct adipose-derived stem cells (ADSCs) differentiation into a variety of specialized cells for tissue engineering and regenerative medicine applications. Additionally, the review discusses the limitations of cell-imprinted PDMS substrates and highlights the efforts made to overcome these limitations.

Long non-coding RNA (lncRNA) MALAT1 in regulating osteogenic and adipogenic differentiation using a double-stranded gapmer locked nucleic acid nanobiosensor

Long non-coding RNAs (lncRNA) are non-protein coding RNA molecules that are longer than 200 nucleotides. The lncRNA molecule plays diverse roles in gene regulation, chromatin remodeling, and cellular processes, influencing various biological pathways. However, probing the complex dynamics of lncRNA in live cells is a challenging task. In this study, a double-stranded gapmer locked nucleic acid (ds-GapM-LNA) nanobiosensor is designed for visualizing the abundance and expression of lncRNA in live human bone-marrow-derived mesenchymal stem cells (hMSCs). The sensitivity, specificity, and stability were characterized. The results showed that this ds-GapM-LNA nanobiosensor has very good sensitivity, specificity, and stability, which allows for dissecting the regulatory roles of cellular processes during dynamic physiological events. By incorporating this nanobiosensor in living hMSC imaging, we elucidated lncRNA MALAT1 expression dynamics during osteogenic and adipogenic differentiation. The data reveal that lncRNA MALAT1 expression is correlated with distinct sub-stages of osteogenic and adipogenic differentiation.

Regulation of cell fate by cell imprinting approach in vitro

Cell culture-based technologies are widely utilized in various domains such as drug evaluation, toxicity assessment, vaccine and biopharmaceutical development, reproductive technology, and regenerative medicine. It has been demonstrated that pre-adsorption of extracellular matrix (ECM) proteins including collagen, laminin and fibronectin provide more degrees of support for cell adhesion. The purpose of cell imprinting is to imitate the natural topography of cell membranes by gels or polymers to create a reliable environment for the regulation of cell function. The results of recent studies show that cell imprinting is a tool to guide the behavior of cultured cells by controlling their adhesive interactions with surfaces. Therefore, in this review we aim to compare different cell cultures with the imprinting method and discuss different cell imprinting applications in regenerative medicine, personalized medicine, disease modeling, and cell therapy.

Engineered substrates incapable of induction of chondrogenic differentiation compared to the chondrocyte imprinted substrates

It is well established that surface topography can affect cell functions. However, finding a reproducible and reliable method for regulating stem cell behavior is still under investigation. It has been shown that cell imprinted substrates contain micro- and nanoscale structures of the cell membrane that serve as hierarchical substrates, can successfully alter stem cell fate. This study investigated the effect of the overall cell shape by fabricating silicon wafers containing pit structure in the average size of spherical-like chondrocytes using photolithography technique. We also used chondrocyte cell line (C28/I2) with spindle-like shape to produce cell imprinted substrates. The effect of all substrates on the differentiation of adipose-derived mesenchymal stem cells (ADSCs) has been studied. The AFM and scanning electron microscopy images of the prepared substrates demonstrated that the desired shapes were successfully transferred to the substrates. Differentiation of ADSCs was investigated by immunostaining for mature chondrocyte marker, collagen II, and gene expression of collagen II, Sox9, and aggrecan markers. C28/I2 imprinted substrate could effectively enhanced chondrogenic differentiation compared to regular pit patterns on the wafer. It can be concluded that cell imprinted substrates can induce differentiation signals better than engineered lithographic substrates. The nanostructures on the cell-imprinted patterns play a crucial role in harnessing cell fate. Therefore, the patterns must include the nano-topographies to have reliable and reproducible engineered substrates.

Progress of Microfluidic Hydrogel-Based Scaffolds and Organ-on-Chips for the Cartilage Tissue Engineering

Cartilage degeneration is among the fundamental reasons behind disability and pain across the globe. Numerous approaches have been employed to treat cartilage diseases. Nevertheless, none have shown acceptable outcomes in the long run. In this regard, the convergence of tissue engineering and microfabrication principles can allow developing more advanced microfluidic technologies, thus offering attractive alternatives to current treatments and traditional constructs used in tissue engineering applications. Herein, the current developments involving microfluidic hydrogel-based scaffolds, promising structures for cartilage regeneration, ranging from hydrogels with microfluidic channels to hydrogels prepared by the microfluidic devices, that enable therapeutic delivery of cells, drugs, and growth factors, as well as cartilage-related organ-on-chips are reviewed. Thereafter, cartilage anatomy and types of damages, and present treatment options are briefly overviewed. Various hydrogels are introduced, and the advantages of microfluidic hydrogel-based scaffolds over traditional hydrogels are thoroughly discussed. Furthermore, available technologies for fabricating microfluidic hydrogel-based scaffolds and microfluidic chips are presented. The preclinical and clinical applications of microfluidic hydrogel-based scaffolds in cartilage regeneration and the development of cartilage-related microfluidic chips over time are further explained. The current developments, recent key challenges, and attractive prospects that should be considered so as to develop microfluidic systems in cartilage repair are highlighted.

Notch signaling and fluid shear stress in regulating osteogenic differentiation

Osteoporosis is a common bone and metabolic disease that is characterized by bone density loss and microstructural degeneration. Human bone marrow-derived mesenchymal stem cells (hMSCs) are multipotent progenitor cells with the potential to differentiate into various cell types, including osteoblasts, chondrocytes, and adipocytes, which have been utilized extensively in the field of bone tissue engineering and cell-based therapy. Although fluid shear stress plays an important role in bone osteogenic differentiation, the cellular and molecular mechanisms underlying this effect remain poorly understood. Here, a locked nucleic acid (LNA)/DNA nanobiosensor was exploited to monitor mRNA gene expression of hMSCs that were exposed to physiologically relevant fluid shear stress to examine the regulatory role of Notch signaling during osteogenic differentiation. First, the effects of fluid shear stress on cell viability, proliferation, morphology, and osteogenic differentiation were investigated and compared. Our results showed shear stress modulates hMSCs morphology and osteogenic differentiation depending on the applied shear and duration. By incorporating this LNA/DNA nanobiosensor and alkaline phosphatase (ALP) staining, we further investigated the role of Notch signaling in regulating osteogenic differentiation. Pharmacological treatment is applied to disrupt Notch signaling to investigate the mechanisms that govern shear stress induced osteogenic differentiation. Our experimental results provide convincing evidence supporting that physiologically relevant shear stress regulates osteogenic differentiation through Notch signaling. Inhibition of Notch signaling mediates the effects of shear stress on osteogenic differentiation, with reduced ALP enzyme activity and decreased Dll4 mRNA expression. In conclusion, our results will add new information concerning osteogenic differentiation of hMSCs under shear stress and the regulatory role of Notch signaling. Further studies may elucidate the mechanisms underlying the mechanosensitive role of Notch signaling in stem cell differentiation.

Molecular imprinting as a simple way for the long-term maintenance of the stemness and proliferation potential of adipose-derived stem cells: an in vitro study

Culturing adipose-derived stem cells (ADSCs) on the biomimetic ADSC-imprinted substrate is a simple way for long-term maintenance of their stemness and proliferation potential.

Computational and experimental studies of a cell-imprinted-based integrated microfluidic device for biomedical applications

It has been proved that cell-imprinted substrates molded from template cells can be used for the re-culture of that cell while preserving its normal behavior or to differentiate the cultured stem cells into the template cell. In this study, a microfluidic device was presented to modify the previous irregular cell-imprinted substrate and increase imprinting efficiency by regular and objective cell culture. First, a cell-imprinted substrate from template cells was prepared using a microfluidic chip in a regular pattern. Another microfluidic chip with the same pattern was then aligned on the cell-imprinted substrate to create a chondrocyte-imprinted-based integrated microfluidic device. Computational fluid dynamics (CFD) simulations were used to obtain suitable conditions for injecting cells into the microfluidic chip before performing experimental evaluations. In this simulation, the effect of input flow rate, number per unit volume, and size of injected cells in two different chip sizes were examined on exerted shear stress and cell trajectories. This numerical simulation was first validated with experiments with cell lines. Finally, chondrocyte was used as template cell to evaluate the chondrogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) in the chondrocyte-imprinted-based integrated microfluidic device. ADSCs were positioned precisely on the chondrocyte patterns, and without using any chemical growth factor, their fibroblast-like morphology was modified to the spherical morphology of chondrocytes after 14 days of culture. Both immunostaining and gene expression analysis showed improvement in chondrogenic differentiation compared to traditional imprinting methods. This study demonstrated the effectiveness of cell-imprinted-based integrated microfluidic devices for biomedical applications.

Molecular Imprinting Strategies for Tissue Engineering Applications: A Review

Tissue Engineering (TE) represents a promising solution to fabricate engineered constructs able to restore tissue damage after implantation. In the classic TE approach, biomaterials are used alongside growth factors to create a scaffolding structure that supports cells during the construct maturation. A current challenge in TE is the creation of engineered constructs able to mimic the complex microenvironment found in the natural tissue, so as to promote and guide cell migration, proliferation, and differentiation. In this context, the introduction inside the scaffold of molecularly imprinted polymers (MIPs)—synthetic receptors able to reversibly bind to biomolecules—holds great promise to enhance the scaffold-cell interaction. In this review, we analyze the main strategies that have been used for MIP design and fabrication with a particular focus on biomedical research. Furthermore, to highlight the potential of MIPs for scaffold-based TE, we present recent examples on how MIPs have been used in TE to introduce biophysical cues as well as for drug delivery and sequestering.