A major challenge in hematologic disease research is the development of model systems that accurately replicate human pathophysiology in vivo. Recent advancements in three-dimensional (3D) ex vivo modeling using human-induced pluripotent stem cell (iPSC)-derived bone marrow organoids provide a physiologically relevant approach to studying hematologic diseases.

Innovations in Bone Marrow Organoid Models

Recent studies have demonstrated that human iPSCs cultured in a hydrogel matrix enriched with human Collagen I (VitroCol, #5007-20mL) and human Collagen IV (#5022) support the formation of vascularized, myelopoietic bone marrow organoids. These matrices provide an optimized extracellular environment essential for the development of mesenchymal stromal cells, fibroblasts, endothelial cells, and hematopoietic cells, closely resembling the native bone marrow niche.[1-3]

Bone Marrow Organoids as a Platform for Hematologic Malignancies

Bone marrow organoids have been successfully used to support the engraftment, survival, and proliferation of hematopoietic stem and progenitor cells as well as primary cells from patients with myeloid and lymphoid blood cancers.[1]

Furthermore, it has been demonstrated that hematopoietic stem and progenitor cells (HSPCs) from patients with myelodysplastic syndromes (MDSs) efficiently engraft into bone marrow organoids, biomimicking the disease’s pathophysiology.[3]

The ability of these organoids to autonomously maintain hematopoiesis and sustain the marrow microenvironment underscores their potential as a transformative model for studying hematopoietic disorders and evaluating novel therapeutic strategies.

References

[1] Khan, A. et al. Cancer Discov (2023) 13 (2): 364–385 https://doi.org/10.1158/2159-8290.CD-22-0199
[2] Olijnik, AA. et al. Nature Protocols (2024) 19: 2117–2146 https://doi.org/10.1038/s41596-024-00971-7
[3] Ren, K. et al.  Blood Adv (2025) 9 (1): 54–65

Papain, a proteolytic enzyme derived from the papaya fruit (Carica papaya latex), provides a gentle and efficient method for dissociating tissues into single cells, while preserving cell integrity and viability for downstream applications.

Advantages of Papain in Tissue Dissociation:

1. Broad Specificity and Versatility
   Papain exhibits broad substrate specificity, cleaving various peptide bonds in proteins found within the extracellular matrix and cell-cell adhesions. This versatility makes it suitable for dissociating tissues from a wide variety of species, including common models like rat, mouse, and human, as well as less common species such as shellfish, salamander, turtle, and insect.

2. Gentle Proteolysis
   Papain breaks down proteins in a mild and controlled manner, minimizing damage to cell membranes. This is particularly beneficial for isolating delicate cells, such as cortical neurons, retinal cells, and photoreceptors, or endocrine cells, which require gentle handling to maintain functionality.

3. High Cell Viability
   Papain’s gentle action ensures high cell viability, preserving isolated cells for downstream applications such as cell culture, flow cytometry, and molecular analyses.

4. High Efficiency
   Papain efficiently degrades extracellular matrix proteins, enabling the dissociation of tissues into single cells under near-physiological conditions. It is particularly effective for tissues that are challenging to dissociate or are available in limited quantities.

5. Consistency and Reproducibility
   Papain is available in standardized formulations (lyophilized or suspension), ensuring batch-to-batch consistency and reproducibility. Ready-to-use kits, optimized for isolating viable single cells from fetal and neonatal central nervous system tissues, further streamline the process based on well-established protocols.

Available Papain Products

• Lyophilized and Suspension: available in 25 mg, 100 mg and 1 g.
  • Papain Suspension, twice crystallized, 0,22 µm filtered
  • Papain Lyophilized Powder, twice crystallized
• Papain Dissociation System (PDS and PDS2 Kits):
  The PDS and PDS2 Kits ensure consistent, reliable results, saving time and effort in tissue dissociation. With its user-friendly protocols and high-quality components, these kits offer ready-to-use solutions for neural tissue dissociation. They are based on the method developed by Huettner and Baughman (J Neurosci. 1986;6(10):3044-3060), optimized to isolate high yields of viable, morphologically intact cortical neurons from postnatal rats. This technique has also been adapted for the dissociation of other brain regions, including the hippocampus, as well as various fetal and postnatal brain tissues.

Optimized Use and Combinations

While Papain is highly effective on its own, it can also be used in combination with other enzymes like Collagenase, Trypsin or Dispase, depending on experimental needs.

The Tissue Dissociation Guide is a comprehensive resource that details protocols and techniques for enzymatically dissociating tissues into single cells.

3D cell cultures are evolving rapidly, offering increasingly complex systems that closely mimic the structure, microenvironment, and physiological functions of human organs and tissues. These models enable the study of spatial cell organization, organ and disease development, and provide powerful tools for drug screening, toxicity assessment, and transplantation research.
By combining relevant cell types, media, extracellular matrices or bioprinted structures, researchers can simulate natural environments with high accuracy. To date, numerous models of human tissues and organs, both in healthy and diseased states, have been successfully developed.
These include:

Solutions from CellSystems®
CellSystems offers high-quality products suited for 3D cell culture applications:

References:

[1] Olijnik, A., et al. Nature Protocols, 19(7), 2024, 2117–46. https://doi.org/10.1038/s41596-024-00971-7
[2] Maulana, T., et al. Cell Stem Cell, 31(7) 2024, 989-1002.e9. https://doi.org/10.1016/j.stem.2024.04.018
[3] Donadoni, M., et al. Journal of NeuroVirology, 2024. https://doi.org/10.1007/s13365-024-01204-z
[4] Mitrofanova, O., et al. Cell Stem Cell, 31(8), 2024, 1175-1186.e7. https://doi.org/10.1016/j.stem.2024.05.007                                  
[5] Petrachi, T., et al. Biomedicine & Pharmacotherapy, 165, 2023, 115146. https://doi.org/10.1016/j.biopha.2023.115146
[6] Mou, X., et al.  Science Advances, 10(23), 2024, eadn2689 https://doi.org/10.1126/sciadv.adn2689
[7] Xie, L., et al. Environmental Health Perspectives, 128(6), 2020, 067008. https://doi.org/10.1289/EHP6471                                         
[8] Nie, J., et al. Advanced Science, 11(30), 2024, 2400970. https://doi.org/10.1002/advs.202400970
[9] Chettouh-Hammas, N., et al.  Ed N. Ismail. Oxidative Medicine and Cellular Longevity. 2023, 1–15. https://doi.org/10.1155/2023/6829931                 
[10] Sun, S., et al. Nature Communications, 13(1), 2022, 5481. https://doi.org/10.1038/s41467-022-33114-1                                          
[11] Varone, A., et al. Biomaterials, 275, 2021, 120957. https://doi.org/10.1016/j.biomaterials.2021.120957
[12] Seyfoori, A. et al. bioRxiv preprint, 2024. https://doi.org/10.1101/2024.04.15.589651
[13] Mahajan G, et al. Microbiome. 2022, 26;10(1):201. doi: 10.1186/s40168-022-01400-1
[14] Gutzeit, O. et al. Systems Biology, 23, 2023, https://doi.org/10.1101/2023.11.22.568273.