Non-invasive, in vitro functional tissue assay systems

1. An in vitro method for screening a test substance for an effect on a cardiomyocyte, comprising:

(a) providing cardiomyocytes having been obtained by differentiating mouse or human pluripotent stem cells;

wherein the stem cells have been transfected with at least one vector, wherein the at least one vector comprises a first nucleotide sequence encoding a selectable marker and the at least one vector comprises a second nucleotide sequence encoding a reporter gene;

wherein the transfected stem cells comprise the first nucleotide sequence operably linked to at least one cardiac cell-specific regulatory sequence and comprise the second nucleotide sequence operably linked to a cardiac cell-specific regulatory sequence, and

wherein the cardiomyocytes have been selected based on expression of the selectable marker;

(b) contacting cardiomyocytes of step (a) with a test substance, wherein the cardiomyocytes have been placed on an electrode array;

(c) measuring the electrical activity of the contacted cardiomyocytes with the electrode array and analyzing at least one parameter selected from the group consisting of:

(i) Na + channel activity,

(ii) Ca2 + /K + channel activity,

(iii) K + channel activity;

(iv) amplitude and/or field potential duration,

(v) chronotropy,

(vi) arrhythmia,

(vii) pH-value,

(viii) oxygen partial pressure,

(ix) beating arrest,

(x) contractility,

(xi) analysis of AV-dissociation contractility,

(xii) conductivity and/or impedance,

(xiii) nitrous oxide-effects, or

(ix) morphological changes;

(d) selecting a test substance that has an effect on at least one parameter in step (c) as compared to cardiomyocytes which were not contacted with a test substance and wherein a change in at least one parameter measured in step (c) indicates that the test substance has an effect on a cardiomyocyte.

2. The assay method of claim 1 , wherein said pluripotent stem cells are embryonic stem (ES) cells.

3. The method of claim 1 , wherein said electrode array is a multi- or microelectrode array (MEA).

4. The method of claim 3 , wherein the electrode array is coated with fibronectin.

5. The method of claim 1 , wherein at least one of the parameters analyzed is selected from the group consisting of: beating frequency, mean contractility, maximum contraction and mean area of contraction is analyzed.

6. The method of claim 1 , wherein test substance is one of a collection of test substances.

7. The method of claim 6 , wherein said collection of test substances comprises about 10 3 to about 10 5 substances.

8. The method of claim 1 , wherein three or more measurements are taken.

9. The method of claim 1 , further comprising isolating the measured cardiomyocytes.

10. The method of claim 8 , wherein said measurements are taken at different positions within the array.

11. The method of claim 1 , wherein said selection step positively screens a test substance.

12. The method of claim 1 , wherein said selection step screens out a test substance.