Perivascular Secretome Influences Hematopoietic Stem Cell Maintenance in a Gelatin Hydrogel

Abstract

Adult hematopoietic stem cells (HSCs) produce the body's full complement of blood and immune cells. They reside in specialized microenvironments, or niches, within the bone marrow. The perivascular niche near blood vessels is believed to help maintain primitive HSCs in an undifferentiated state but demonstration of this effect is difficult. In vivo studies make it challenging to determine the direct effect of the endosteal and perivascular niches as they can be in close proximity, and two-dimensional in vitro cultures often lack an instructive extracellular matrix environment. We describe a tissue engineering approach to develop and characterize a three-dimensional perivascular tissue model to investigate the influence of the perivascular secretome on HSC behavior. We generate 3D endothelial networks in methacrylamide-functionalized gelatin hydrogels using human umbilical vein endothelial cells (HUVECs) and mesenchymal stromal cells (MSCs). We identify a subset of secreted factors important for HSC function, and examine the response of primary murine HSCs in hydrogels to the perivascular secretome. Within 4 days of culture, perivascular conditioned media promoted maintenance of a greater fraction of hematopoietic stem and progenitor cells. This work represents an important first-generation perivascular model to investigate the role of niche secreted factors on the maintenance of primary HSCs.

Crosstalk between microglia and patient-derived glioblastoma cells inhibit invasion in a three-dimensional gelatin hydrogel model

“…We have previously developed a family of gelatin hydrogels to investigate pathophysiological processes underlying glioblastoma invasion and progression. Extensive biophysical performance data has previously been reported including network architecture and mechanical performance [52,53], water and small-molecule diffusivity [54][55][56], and the capacity to support growth and phenotypic studies of primary glioblastoma cells and cells from the neurovascular unit [57,58]. For this project, GBM and MG cells were maintained in three-dimensional culture in a 4 wt% methacrylamide-functionalized gelatin (GelMA) that exhibited a physiologically relevant Young's modulus (1.04 ± 0.10 kPa; n = 14; Fig.…”

Evaluation of P. aeruginosa attachment on mineralized collagen scaffolds and addition of manuka honey to increase mesenchymal stem cell osteogenesis

“…Other scaffolds fabricated with manuka honey have demonstrated clearance of S. aureus at higher concentrations >10%, however, the effect of this concentration on the regeneration of bone and bone cell health has not been investigated [23, 26]. Additionally, there is significant opportunity to better understand the impact of honey on endothelial vasculature formation using a range of recent advances in three-dimensional vessel imaging [84] and quantitative assessment [85].…”

Engineering of fully humanized and vascularized 3D bone marrow niches sustaining undifferentiated human cord blood hematopoietic stem and progenitor cells

“…Some of these approaches have been developed to study hematopoietic cell trafficking and thrombopoiesis mechanisms, 35 but they often rely on the addition of MSCs, which under specific culture conditions can serve as perivascular cells. 20,22 This often requires complex medium compositions to match the different cell types requirements. 36 Furthermore, these approaches lack the osteoblastic cells typically found in native human BM.…”

“…17 In contrast, 3D in vitro culture systems with engineered perivascular niches offer a model to study human hematopoiesis in long-term controlled settings, but they often rely on the use of Human Umbilical Vein Endothelial cells (HUVECs) to construct the capillary networks, requiring thus an additional source of perivascular cells (normally BM-MSCs) and complex medium compositions with angiogenic factors. [18][19][20][21][22] We previously developed a 3D angiogenic niche that bypasses this constraint by culturing the stromal vascular fraction (SVF) cells from human adipose tissue on collagen scaffolds and inside perfusion bioreactors. 23 The SVF is a heterogenous mix of pericytes, mesenchymal stromal cells (MSCs), mature endothelial cells and endothelial progenitor cells 24,25 that reproducibly promotes the formation of vascular structures (endothelium + perivascular cells) and the release of angiogenic factors in vitro.…”