Overcoming challenges in the isolation of UC-MSCs

The therapeutic potential of mesenchymal stem cells (MSCs) has been extensively explored. Their ability to promote tissue repair and regeneration has led to MSC-based therapies being trialed in the treatment of various immune disorders, cardiac injury, and brain injury. These multipotent cells can be isolated from a variety of sources, including the bone marrow, adipose tissue, placenta, dental pulp, and the umbilical cord (1).

Umbilical-cord derived MSCs (UC-MSCs) represent a particularly valuable source of stem cells for regenerative medicine. The collection of UC-MSCs is not associated with the same ethical and practical issues as the isolation of cells from other sources, as the collection is non-invasive, and the umbilical cord is typically discarded after birth and considered medical waste. Aside from these technical advantages, UC-MSCs also possess a broad self-renewal capacity, comparable to the more ethically complicated embryonic stem cells (1).

Isolating UC-MSCs

One of the challenges in working with umbilical cord tissue is in collecting sufficient MSCs from the material. There are two primary methods for isolating UC-MSCs: the explant method and the enzymatic digestion method. The enzymatic digestion method involves using enzymes to dissociate the cells from the tissue (1). This technique has been associated with potential cell viability issues as well as reduced proliferation of the isolated cells (2).

The explant method involves manual dissection of the tissues into fragments followed by seeding into culture dishes. This is a simpler method of isolation but is limited by reduced cell numbers due to cells becoming detached and floating in the culture medium. MSCs cannot effectively migrate from tissues that do not adequately adhere to the surface, resulting in reduced cell recovery and inconsistencies in the isolation procedure (1,2).

The isolation of MSCs by the explant method often results in cells becoming detached from the culture dish.

A simple solution to a complex problem

To overcome this challenge, researchers at the University of Tokyo designed an enhanced explant protocol that promotes efficient attachment of the UC tissue fragments to the dish (2). To prevent the loss of cells due to tissues failing to adhere, they overlayed the plated tissue fragments with a simple stainless-steel mesh (Cellamigo®). This mesh encouraged the adherence of the tissue to the plate and enhanced UC-MSC migration, allowing them to isolate greater numbers of UC-MSCs more quickly (2). Importantly, the UC-MSCs obtained in this manner retained the same immunosuppressive and multipotent features as conventionally isolated UC-MSCs (2).

The improved explant method has since been used by the same research group to demonstrate the neuroprotective effects of UC-MSCs on oxygen-glucose deprived (OGD) neurons in a mouse model of ischemic brain injury (3). They used the Cellamigo® mesh to successfully isolated UC-MSCs and performed co-culture experiments with neonatal cortical neurons injured by OGD. Additionally, UC-MSCs derived in this way were delivered intravenously to mice in a model of neonatal stroke, with researchers finding that they were safe and had promising beneficial effects (4). Most recently, the improved explant method was used to isolate UC-MSCs to use as a potential therapy in a model of fetal growth restriction (FGR). The results indicated that UC-MSCs limited the neurological impairments associated with FGR (5).

Innovation in all aspects of biomedicine is essential for continued progress in advanced therapeutics. Even simple solutions to overcome practical challenges in cell culture can have far-reaching effects in regenerative medicine.

References

1. Nagamura-Inoue, T. Umbilical cord-derived mesenchymal stem cells: Their advantages and potential clinical utility. World J. Stem Cells 6, 195 (2014). doi: 10.4252/wjsc.v6.i2.195

2. Mori, Y. et al. Improved explant method to isolate umbilical cord-derived mesenchymal stem cells and their immunosuppressive properties. Tissue Eng. - Part C Methods 21, 367–372 (2015). doi: 10.1089/ten.TEC.2014.0385

3. Mukai, T., Tojo, A. & Nagamura-Inoue, T. Umbilical Cord-Derived Mesenchymal Stromal Cells Contribute to Neuroprotection in Neonatal Cortical Neurons Damaged by Oxygen-Glucose Deprivation. Front. Neurol. 9, 466 (2018). doi: 10.3389/fneur.2018.00466

4. Tanaka, E. et al. Dose-dependent effect of intravenous administration of human umbilical cord-derived mesenchymal stem cells in neonatal stroke mice. Front. Neurol. 9, 1 (2018). doi: 10.3389/fneur.2018.00133

5. Kitase, Y. et al. Establishment of a Novel Fetal Growth Restriction Model and Development of a Stem-Cell Therapy Using Umbilical Cord-Derived Mesenchymal Stromal Cells. Front. Cell. Neurosci. 14, (2020). doi: 10.3389/fncel.2020.00212