Engineered tissue constructs

1. A method of forming a modular engineered tissue construct, the method comprising:

providing a plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates, at least one cell aggregate including a plurality of cells and a plurality of biocompatible and biodegradable nanoparticles and/or microparticles that are incorporated within the cell aggregates, wherein at least one of the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates is formed by:

culturing a suspension of nanoparticles and/or microparticles and undifferentiated and/or substantially differentiated progenitor cells in an annular well to form a ring-shaped, self-assembled, scaffold-free, high-density cell aggregate; and

removing the ring-shaped, self-assembled, scaffold-free, high-density cell aggregate;

the nanoparticles and/or microparticles acting as a bulking agent within the cell aggregate to increase the cell aggregate size and/or thickness and improve the mechanical properties of the cell aggregate; and

the nanoparticles and/or microparticles including at least one bioactive agent for delivery of the at least one bioactive agent wherein the at least one bioactive agent is differentially and/or controllably released by the nanoparticles and/or microparticles;

stacking the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates on a support; and

culturing the stacked ring-shaped, self-assembled, scaffold-free, high-density cell aggregates on the solid support in a culture medium to fuse the aggregates and promote tissue formation.

2. The method of claim 1 , wherein the at least one of the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates is formed by:

providing undifferentiated and/or substantially differentiated progenitor cells;

combining the undifferentiated and/or substantially differentiated progenitor cells with a plurality of nanoparticles and/or microparticles so that the nanoparticles and/or microparticles are dispersed and suspended with the undifferentiated and/or substantially differentiated progenitor cells in a culture medium; and

culturing the suspension of nanoparticles and/or microparticles and undifferentiated and/or substantially differentiated progenitor cells in an annular well to form a ring-shaped, self-assembled, scaffold : free, high : density cell aggregate.

3. The method of claim 1 , wherein the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates comprise differing aggregate materials to form a heterogeneous tissue construct, at least one of the ring-shaped, self-assembled, scaffold-free, high-density cell aggregates being provided or formed with or without nanoparticles and/or microparticles and having different properties than the other aggregates to vary the properties of the construct for particular tissue engineering application.

4. The method of claim 1 , wherein the at least one of the fused self-assembled, scaffold-free, high-density cell aggregates comprises a plurality of chondrogenic cells.

5. The method of claim 3 , wherein the stacked, ring-shaped, self-assembled, scaffold-free, high-density cell aggregates includes alternating first engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates and second engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates, wherein the first and second engineered stacked ring-shaped, self-assembled, scaffold-free, high-density cell aggregates form heterogeneous tubular shaped construct.

6. The method of claim 5 , wherein the first engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates define cartilaginous portions within the tubular shaped construct and the second engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates define noncartilaginous portions within the tubular shaped construct, wherein the first and second engineered stacked ring-shaped, self-assembled, scaffold-free, high-density cell aggregates are arranged end-to-end in an alternating manner.

7. The method of claim 1 , the nanoparticles and/or microparticles comprising a biocompatible and biodegradable polymer.

8. The method of claim 1 , bioactive agent including at least one of TGF-β1 and/or BMP-2.

9. The method of claim 5 , the plurality of cells in the first engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates consisting of a plurality of chondrogenic cells and the plurality of cells in the second engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates consisting of non-chondrogenic cells.

10. The cells according to claim 9 , the chondrogenic cells selected from the group consisting of mesenchymal stem cells.

11. The cells according to claim 9 , the non-chondrogenic cells being vascular progenitor cells selected from the group consisting of human umbilical vein endothelial cells and/or smooth muscle cells.

12. A method of forming a heterogeneous modular engineered tissue construct, the method comprising;

providing a plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates, at least one cell aggregate including a plurality of cells and a plurality of biocompatible and biodegradable nanoparticles and/or microparticles that are incorporated within the cell aggregates, wherein at least one of the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates is formed by:

culturing a suspension of nanoparticles and/or microparticles and undifferentiated and/or substantially differentiated progenitor cells in an annular well to form a ring-shaped, self-assembled, scaffold-free, high-density cell aggregate; and

removing the ring-shaped, self-assembled, scaffold-free, high-density cell aggregate;

the nanoparticles and/or microparticles acting as a bulking agent within the cell aggregate to increase the cell aggregate size and/or thickness and improve the mechanical properties of the cell aggregate; and

the nanoparticles and/or microparticles including at least one bioactive agent for delivery of the at least one bioactive agent, wherein the at least one bioactive agent is differentially and/or controllably released by the nanoparticles and/or microparticles;

stacking the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates on a support; and

culturing the stacked ring-shaped, self-assembled, scaffold-free, high-density cell aggregates on the solid support in a culture medium to fuse the aggregates and promote tissue formation, wherein the stacked, ring-shaped, self-assembled, scaffold-free, high-density cell aggregates include alternating first engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates and second engineered ring-shaped, self-assembled, scaffold-free, high-density cell aggregates, wherein the first and second engineered stacked ring-shaped, self-assembled, scaffold-free, high-density cell aggregates form a heterogeneous tubular shaped construct;

wherein the plurality of ring-shaped, self-assembled, scaffold-free, high-density cell aggregates comprise differing aggregate materials, at least one of the ring-shaped self-assembled, scaffold-free, high-density cell aggregates being provided or formed with or without nanoparticles and/or microparticles and having different properties than the other aggregates to vary the properties of the construct for particular tissue engineering application.