A modular versatile chip carrier for high-throughput screening of cell-biomaterial interactions

Designed Surface Topographies Control ICAM-1 Expression in Tonsil-Derived Human Stromal Cells

Fibroblastic reticular cells (FRCs), the T-cell zone stromal cell subtype in the lymph nodes, create a scaffold for adhesion and migration of immune cells, thus allowing them to communicate. Although known to be important for the initiation of immune responses, studies about FRCs and their interactions have been impeded because FRCs are limited in availability and lose their function upon culture expansion. To circumvent these limitations, stromal cell precursors can be mechanotranduced to form mature FRCs. Here, we used a library of designed surface topographies to trigger FRC differentiation from tonsil-derived stromal cells (TSCs). Undifferentiated TSCs were seeded on a TopoChip containing 2176 different topographies in culture medium without differentiation factors, then monitored cell morphology and the levels of ICAM-1, a marker of FRC differentiation. We identified 112 and 72 surfaces that upregulated and downregulated, respectively, ICAM-1 expression. By monitoring cell morphology, and expression of the FRC differentiation marker ICAM-1 via image analysis and machine learning, we discovered correlations between ICAM-1 expression, cell shape and design of surface topographies and confirmed our findings by using flow cytometry. Our findings confirmed that TSCs are mechano-responsive cells and identified particular topographies that can be used to improve FRC differentiation protocols.

Muscle-Secreted Factors Improve Anterior Cruciate Ligament Graft Healing: An In Vitro and In Vivo Analysis

One of the ligaments most often damaged during sports-the anterior cruciate ligament (ACL)-has poor healing capacity. On damage, reconstructive surgery is performed to restore the mechanical stability of the knee and to reduce the inflammatory milieu otherwise present in the joint. A return to normal activities, however, takes between 9 and 12 months. Thus, strategies capable of improving ACL graft healing are needed. Embryonic development of tendon and ligament (T/L) is regulated by a crosstalk between different cell types. We hypothesized that terminally differentiated skeletal-derived cells such as osteoblasts, chondrocytes, and myoblasts modulate T/L healing. Using an indirect coculture system, we discovered that myoblast-secreted signals-but not osteoblasts, chondrocytes, or stromal-secreted signals-are capable of upregulating classical T/L markers such as scleraxis and tenomodulin on human hamstring tendon-derived cells (hTC), which contribute to ACL graft healing. Transcriptome analysis showed that coculturing hTC with myoblasts led to an upregulation of extracellular matrix (ECM) genes and resulted in enhanced ECM deposition. In vivo, using a rat model of ACL reconstruction showed that conditioned media derived from human muscle tissue accelerated femoral tunnel closure, a key step for autograft integration. Collectively, these results indicate that muscle-secreted signals can be used to improve ACL graft healing in a clinical setting where muscle remnants are often discarded.

Biomimetic strategies for fracture repair: Engineering the cell microenvironment for directed tissue formation

Complications resulting from impaired fracture healing have major clinical implications on fracture management strategies. Novel concepts taken from developmental biology have driven research strategies towards the elaboration of regenerative approaches that can truly harness the complex cellular events involved in tissue formation and repair. Advances in polymer technology and a better understanding of naturally derived scaffolds have given rise to novel biomaterials with an increasing ability to recapitulate native tissue environments. This coupled with advances in the understanding of stem cell biology and technology has opened new avenues for regenerative strategies with true clinical translatability. These advances have provided the impetus to develop alternative approaches to enhance the fracture repair process. We provide an update on these advances, with a focus on the development of novel biomimetic approaches for bone regeneration and their translational potential.

Polymer microarray technology for stem cell engineering

Stem cells hold remarkable promise for applications in tissue engineering and disease modeling. During the past decade, significant progress has been made in developing soluble factors (e.g., small molecules and growth factors) to direct stem cells into a desired phenotype. However, the current lack of suitable synthetic materials to regulate stem cell activity has limited the realization of the enormous potential of stem cells. This can be attributed to a large number of materials properties (e.g., chemical structures and physical properties of materials) that can affect stem cell fate. This makes it challenging to design biomaterials to direct stem cell behavior. To address this, polymer microarray technology has been developed to rapidly identify materials for a variety of stem cell applications. In this article, we summarize recent developments in polymer array technology and their applications in stem cell engineering.

STATEMENT OF SIGNIFICANCE

Stem cells hold remarkable promise for applications in tissue engineering and disease modeling. In the last decade, significant progress has been made in developing chemically defined media to direct stem cells into a desired phenotype. However, the current lack of the suitable synthetic materials to regulate stem cell activities has been limiting the realization of the potential of stem cells. This can be attributed to the number of variables in material properties (e.g., chemical structures and physical properties) that can affect stem cells. Polymer microarray technology has shown to be a powerful tool to rapidly identify materials for a variety of stem cell applications. Here we summarize recent developments in polymer array technology and their applications in stem cell engineering.