08
Nov

Bone Marrow Microenvironment-On-Chip for Culture of Functional Hematopoietic Stem Cells

Can organ on a chip platforms be used to culture and maintain functional hematopoietic stem cells and progenitor cells (HSPC)? This is a recent paper from Sharipol et al. from the University of Rochester, culturing important components of bone marrow microenvironment (BMME) in an organ on a chip. Available 3D bone marrow models lack major BMME components, but the bone marrow on a chip in this study mimics the BMME in a controlled way.

Results
The chip had two compartments: one apical channel and one basal. In the apical channel, after differentiating a supportive osteoblastic layer for 2 weeks, bone marrow cells were suspended in fibrin hydrogel and introduced to the channel. Simultaneously, a supportive endothelial layer was generated in the basal channel. In another set of experiments, instead of the whole bone microenvironment cells, sorted LSK (Lin−Sca+cKit+) HSPCs were added to the apical side. This time, after 2 weeks of culturing these cells, the chip-derived cells (CD45.2+) were mixed with competitor cells (CD45.1+) and transplanted into mice. At the same time, equal numbers of CD45.2+ mouse bone marrow cells were mixed with competitor cells and transplanted into another group of mice as controls. Recipients’ bone marrow and peripheral blood (PB) were analyzed in the short and long term to assess chip-derived HSPCs’ engraftment and repopulation. Later, for long-term HSPC functional investigation, 28 days post-primary transplant, bone marrow cells of primary recipients were injected into secondary recipients for further PB analyses.

organ on a chip, microphysiological systems, microfluidics, tissue chips, bone marrow microenvironment, hematopoietic stem cell, osteoblasts, bone marrow stromal cells, hematopoiesis, mesenchymal stem cells
Figure 1 – Digestible of the organ on a chip assay; schematic of the technology and a summary of the important points in the paper. Adapted from Sharipol A, Lesch ML, Soto CA and Frisch BJ (2022) Bone Marrow Microenvironment-On-Chip for Culture of Functional Hematopoietic Stem Cells. Front. Bioeng. Biotechnol. 10:855777. doi: 10.3389/fbioe.2022.855777; Images were changed for clarity; This article was reproduced under Creative Commons Attribution License (CC BY).

Method
The authors used the microfluidic system from Emulate Bio, added osteoblastic cells, a cell-laden fibrin hydrogel (contained bone marrow stromal cells (BMSC), HSPCs, and other bone marrow cells) and endothelial cells (C166 cell line)

Fabrication method: The chips were bought from Emulate Bio
Sterilization method: The chips were shipped sterile
Cells incorporation: Bone marrow cells have been isolated and 2D cultured for 14 days, endothelial cells were thawed and cultured for 4 days and then were added to the basal channel. The chip was inverted and incubated for 2 hours. The mixture of bone marrow cells and fibrin gel was added to the apical channel.
Perfusion/refreshing method: Connect to reservoirs and perfusion (change medium in reservoirs every 2-3 days)
On-chip read-outs: Microscopy (fix and stain cells in the chip)
Off-chip read-outs: Flow cytometry (Add digestion solution and trypsin and aspirate all the cells from the chip)

Strong points:
+ Automatic perfusion in both channels
+ Microscopy in the chip
+ Ability to harvest cells from the chip
+ Relatively long-term culture

+ Using well-established commercial protocols

Improvement points:
– Recreation BMME-on-chip with human cells
– Not clear how the medium for the cells in the is refreshed
– Would have been interesting to study the role of endothelial cells in the functionality of the HSPCs
– A comparison of the mechanical properties of the fibrin gel to in vivo

Conclusions and outlook
This study’s bone marrow on a chip recapitulates many in vivo cellular interactions. It can be used as a powerful tool to study bone marrow pathologies and test new therapeutics.

Do you have questions about the system in this paper or similar technologies? Or do you want to start with organ on a chip. Feel free to contact us!

Link to paper: https://www.frontiersin.org/articles/10.3389/fbioe.2022.855777/full;
Citation: Sharipol A, Lesch ML, Soto CA and Frisch BJ (2022) Bone Marrow Microenvironment-On-Chip for Culture of Functional Hematopoietic Stem Cells. Front. Bioeng. Biotechnol. 10:855777. doi: 10.3389/fbioe.2022.855777;
This article was reproduced under Creative Commons Attribution License (CC BY).