Living Biomaterials to Engineer Hematopoietic Stem Cell Niches

Abstract

Living biointerfaces are a new class of biomaterials combining living cells and polymeric matrices that can act as biologically active and instructive materials that host and provide signals to surrounding cells. Here, living biomaterials based on Lactococcus lactis to control hematopoietic stem cells in 2D surfaces and 3D hydrogels are introduced. L. lactis is modified to express C-X-C motif chemokine ligand 12 (CXCL12), thrombopoietin (TPO), vascular cell adhesion protein 1 (VCAM1), and the 7th-10th type III domains of human plasma fibronectin (FN III 7-10 ), in an attempt to mimic ex vivo the conditions of the human bone marrow. These results suggest that living biomaterials that incorporate bacteria expressing recombinant CXCL12, TPO, VCAM1, and FN in both 2D systems direct hematopoietic stem and progenitor cells (HSPCs)-bacteria interaction, and in 3D using hydrogels functionalized with full-length human plasma fibronectin allow for a notable expansion of the CD34 + /CD38 -/CD90 + HSPC population compared to the initial population. These results provide a strong evidence based on data that suggest the possibility of using living materials based on genetically engineered bacteria for the ex-vivo expansion of HSPC with eventual practical clinical applications in HSPCs transplantation for hematological disorders.

Engineered Living Materials For Sustainability

“…144 Hay et al engineered the nonpathogenic bacterium Lactobacillus lactis to display recombinant human fibronectin fragments (FNIII 7−10 ) on cell walls. 139,147,148 149 The developed biointerface resembling the bone marrow microenvironment prevented the differentiation of hMSCs and maintained their long-term stem cell phenotype. Thus, the differentiation or stemness of mammalian cells can be tuned ondemand by leveraging the tailor-made living bacterial interface.…”

“…The Spytag peptide can specifically recruit SpyCatcher-modified proteins, nanocrystals, and biopolymers to the lattice surface, thereby creating two-dimensional (2D) living materials for user-defined applications . Hay et al engineered the nonpathogenic bacterium Lactobacillus lactis to display recombinant human fibronectin fragments (FNIII 7–10 ) on cell walls. ,, The formed biofilm-based living biointerface can grow symbiotically with mammalian cells for more advanced medical applications. Briefly, recombinant FNIII 7–10 attached to the bacterial cell wall assisted human mesenchymal stem cells (hMSCs) in adhering to the living interface.…”

Development of an optogenetic gene expression system inLactococcus lactisusing a split photoactivatable T7 RNA polymerase

“…Besides its widespread use in the food industry as a starter culture for the manufacturing of dairy products like buttermilk and cheese, it has gained traction as a live vector for mucosal vaccine delivery(1) and recombinant protein production without the disadvantages of E. coli such as the contamination of the recombinant proteins with lipopolysaccharides that can elicit immune response and inflammation, and the presence of robust protein secretion pathways in L. lactis compared to E. coli (2). L. lactis has been used recently in tissue engineering applications and in engineered living materials (ELMs) (3)(4)(5), a nascent field where a new class of materials based on an inert matrix and a living component, usually engineered using synthetic biology, combine together to produce "smart" functional materials with capabilities that surpass the current state-of-the-art. ELMs are able to respond to environmental physicochemical cues, namely electromagnetic and/or mechanical signals, chemical species and gradients, pH and others.…”

Combining Cryogel Architecture and Macromolecular Crowding‐Enhanced Extracellular Matrix Cues to Mimic the Bone Marrow Niche

“…[ 11,12 ] Therefore, biomaterial‐supported 3D culture systems are increasingly being developed to better reflect the in vivo microenvironment. [ 13 ] Current approaches include: microwell arrays [ 14–19 ] and decellularized ECM matrices [ 20–22 ] as “quasi‐3D models,” fibers and fiber networks as scaffolding material, [ 23,24 ] encapsulation of cells in hydrogels [ 25–30 ] and biocompatible macroporous scaffolds. [ 31–35 ]…”

“…[11,12] Therefore, biomaterial-supported 3D culture systems are increasingly being developed to better reflect the in vivo microenvironment. [13] Current approaches include: microwell arrays [14][15][16][17][18][19] and decellularized ECM matrices [20][21][22] as "quasi-3D models," fibers and fiber networks as scaffolding material, [23,24] encapsulation of cells in hydrogels [25][26][27][28][29][30] and biocompatible macroporous scaffolds. [31][32][33][34][35] Porous 3D scaffolds with defined size, geometry and architecture were fabricated from different materials for engineering the bone marrow HSC-niche.…”