3D printed polycaprolactone (PCL) has potential as a scaffold for bone tissue engineering, but the hydrophobic surface may hinder optimal cell responses. The surface properties can be improved by coating the scaffold with cellulose nanofibrils material (CNF), a multiscale hydrophilic biocompatible biomaterial derived from wood. In this study, human bone marrow-derived mesenchymal stem cells were cultured on tissue culture plates (TCP) and 3D printed PCL scaffolds coated with CNF. Cellular responses to the surfaces (viability, attachment, proliferation and osteogenic differentiation) were documented. CNF significantly enhanced the hydrophilic properties of PCL scaffolds and promoted protein adsorption. Live/dead staining and lactate dehydrogenase release assays confirmed that CNF did not inhibit cellular viability. The CNF between the 3D printed PCL strands and pores acted as a hydrophilic barrier, enhancing cell seeding efficiency and proliferation. CNF supported the formation of a well-organized actin cytoskeleton and cellular production of vinculin protein on the surfaces of TCP and PCL scaffolds.Moreover, CNF-coated surfaces enhanced not only alkaline phosphatase activity, but also collagen Type-I and mineral formation. It is concluded that CNF coating enhances cell attachment, proliferation and osteogenic differentiation and has the potential to improve the performance of 3D printed PCL scaffolds for bone tissue engineering.

A hydrogel that can deliver both proteins and cells enables the local microenvironment of transplanted cells to be manipulated with a single injection. Toward this goal, we designed a hydrogel suitable for the co-delivery of neural stem cells and chondroitinase ABC (ChABC), a potent enzyme that degrades the glial scar that forms after central nervous system (CNS) injury. We leveraged the inverse electron-demand Diels−Alder reaction between norbornene and methylphenyltetrazine to form rapidly gelling (<15 min) crosslinked methylcellulose (MC) hydrogels at physiological temperature and pH, with Young's modulus similar to that of brain tissue (1−3 kPa), and degradable, disulfide-containing crosslinkers. To achieve tunable, affinity-controlled release of a ChABC-Src homology 3 (SH3) fusion protein, we immobilized norbornene-functionalized SH3-binding peptides onto MC-methylphenyltetrazine and observed release of bioactive ChABC-SH3 over 4 days. We confirmed cytocompatibility by evaluating neural progenitor cell survival and proliferation. The combined encapsulation of neural stem cells and chondroitinase ABC from one hydrogel lays the framework for future in vivo studies to treat CNS injuries.

Cholangiocytes form an intricate network of bile ducts to enable proper liver function; yet, recapitulating human stem cell differentiation to cholangiocytes in vitro requires Notch signaling and soluble ligands do not activate the Notch pathway. To overcome these limitations, jagged1 is immobilized on a chemically defined hyaluronan to specifically differentiate human embryonic stem cell‐derived hepatoblasts to cholangiocytes. Hepatoblasts cultured on the jagged1‐hydrogels upregulate Notch target genes and express key cholangiocyte markers including cystic fibrosis transmembrane conductance regulator. Moreover, cholangiocytes adopt morphological changes that resemble liver biliary structures. To emulate natural biliary system development, a new strategy is developed to achieve spatiotemporal control over the Jagged1–Notch2 interaction: jagged1 is first caged with a photocleavable streptavidin and then it is uncaged photochemically to restore the biological function of Jagged1, which is confirmed with Notch2 activation in a fluorescent reporter cell line. Moreover, the differentiation of human embryonic stem cell‐derived hepatoblasts to cholangiocytes is temporally controlled with photochemical uncaging of this streptavidin‐Jagged1‐immobilized hyaluronan hydrogel. This strategy defines a framework to control protein signaling in time and space and specifically for Notch signaling for ultimate use in regenerative medicine strategies of the liver.

Cell-penetrating peptides are a promising therapeutic strategy for a wide variety of degenerative diseases, ageing, and cancer. Among the multitude of cell-penetrating peptides, PepFect14 has been preferentially used in our...