Table 2 Examples for various implantation models in use
| Â | Schematic illustration | Advantages | Physiological process modelling | Disadvantages | Reference |
|---|---|---|---|---|---|
Human/mouse blastocyst |
| - Best recapitulate the morphological features of the blastocyst in vivo | - Embryo implantation | - Ethical issues - Shortage of human blastocysts - Mouse blastocysts have minor difference compared to human | Lalitkumar et al. 2007, Qi, et al. 2014, Ruane, et al. 2020 [73, 102, 103] |
Trophoblast cell line |
| - Easy to acquire - Relatively easy to set up - Allow the 3D modelling of endoglandular invasion by single extravillous trophoblast cells | - Endoglandular invasion by trophoblast cells | - Immortalised cell line may contain genetic aberration | Buck, et al. 2015 [77] |
Trophoblast spheroids |
| - 3D structure better mimic the physiological implantation process - Can be incorporated with stromal cells and ECM (Matrigel /Fibrin) for 3D invasion studies | - Trophoblast invasion and early placentation | - Mainly derived from cell lines with potential genetic aberrations | White, et al. 1988, You, et al. 2019, Akbar, et al. 2020 [8, 104, 105] |
BAP-EB |
| - 3D structure highly recapitulate human blastocyst - Able to attach to endometrial epithelial cells for implantation studies | - Embryo implantation in terms of early adhesion, and attachment to endometrial epithelial cells | - High expertise required - Higher cost due to the need of specific differentiation medium | |
Blastoids |
| - Able to differentiate into both embryonic and extra-embryonic lineages | - Post-implantation development (especially in mouse) | - Extremely high expertise required - Highly complicated experimental set-up - Majority of the studies are in mouse but not in human - May associate with ethical issues | Rivron, et al. 2018, Li, et al. 2019, Sozen, et al. 2019, Yu, et al. 2021 [108,109,110,111] |
