Organ Regeneration Based on Developmental Biology

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access to viable material is limited, particularly from late gestation, and genetic
tools available in mouse such as lineage tracing and reporter tagging have not been
possible. The capacity to apparently generate human kidney cell types in vitro via
the directed differentiation of pluripotent stem cells provides the first opportunity to
examine human kidney development (Fig. 11.4). Indeed, the amenability of iPSC to
CRISPR/Cas9 gene modification may provide an opportunity for lineage analysis
during kidney organoid formation. A number of human iPSC reporter lines have
now been established, primarily as part of the process of developing protocols for
the generation of human iPSC-derived kidney tissue. These include fluorescently
tagged reporters driven from the MIXL1 (Davis et al. 2008 ; Takasato et al. 2014 ),
OSR1 (Mae et al. 2013 ) and NPHS1 promoters (Sharmin et al. 2016 ). An ability to
isolate cells derived using such reporters will facilitate the more stringent charac-
terisation of specific cell types to more thoroughly compare mouse and human and
to also investigate intermediate stages of cell maturation. There is, however, a
‘chicken and egg’ aspect to such studies. We are using our existing understanding of
mouse development, coupled with validated postnatal markers of mature cell type
in both mouse and human, to infer the identity of specific cell types within iPSC-
derived kidney tissue cultures. It remains possible, therefore, that what we are char-
acterising is a synthetic cell type generated as a result of the culture conditions that
may have no genuine counterpart in normal human development. Better under-
standing of human kidney development, therefore, will continue to require valida-
tion in comparison to human material.

Human renal

development

Drug

screening

Disease

modelling

Cellular

replacement

Organoid Bioengineering

Differentiated

cells

iPSC

Patient

Fig. 11.4 Application for kidney organoids generated from human pluripotent stem cells.
Applications include the use of organoids as a whole in nephrotoxicity or drug screening and in
disease modelling using gene edited of patient-derived iPSC. They also serve as a model for kidney
development in the human. The generation of human kidney cell types using organoid differentia-
tion protocols will also provide individual cell types for cell therapy or bioengineering of replace-
ment renal tissue

11 Recapitulating Development to Generate Kidney Organoid Cultures