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← Theoretical 1

Q12 — iPSC/hESC Cardiomyocyte Grafts After Myocardial Infarction

Theoretical 1 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Recombinant DNA & Biotechnology Techniques Cardiovascular Physiology

Groundbreaking studies by Shinya Yamanaka’s group broke the long-standing dogma that differentiated adult cells cannot return to their embryonic state. The creation of induced pluripotent stem cells (iPSCs) offers hope that damaged organs can be repaired by a patient’s own cells. Multiple labs are working on therapies using patient-specific iPSC or immortalized human embryonic stem cell (hESC) lines — including pluripotent stem cell-derived cardiomyocyte grafts to re-muscularize scar tissue after myocardial infarction.

Figure 1. Cross-sections of the ventricular wall of an infarcted heart from a sham-treated monkey. Fig. 1. Cross-section of the ventricular wall of an infarcted heart from a sham-treated monkey.

Figure 2. Cross-sections of the ventricular wall of an infarcted monkey heart with grafts of hESC-derived cardiac myocytes, GFP-labelled. Fig. 2. Cross-section of the ventricular wall of an infarcted monkey heart with grafts of cardiac myocytes derived from hESC. The iPSCs were genetically modified to express green fluorescent protein (GFP).

Using the information and figures, determine whether the following statements are true or false:

A. Assuming ~1/3 of a 120 g left ventricle is lost to a typical infarction, and an average cardiac myocyte size as given, the closest order of magnitude of new cells needed is 10⁹.
B. Although grafted cells are of human origin, the host animals do not require immunosuppression because transplanted cells were derived from embryonic stem cells.
C. Protein identified by blue pseudocolour, abundant in heart scar, is also the most common component of connective tissue.
D. Grafted cardiac myocytes within the host heart can be identified by staining for a cardiac isoform of troponin T.
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Question reproduced from IBO 2022, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)