Inducible Tissue Constructs for Selective Cell Elimination
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Solution Overview
Problem
Current engineered tissue constructs face challenges in controlling tissue organogenesis and expansion, particularly in eliminating unnecessary cell populations and maintaining functional stability, especially in three-dimensional constructs.
Innovation Solution
Incorporating inducible genetic constructs that allow for controlled expression of cell death-inducing polypeptides or nucleic acids, such as caspase 9, activated by chemical inducers of dimerization, to selectively eliminate supporting cells like fibroblasts while maintaining parenchymal cell function, and using angiogenic factors to control tissue expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supporting cells (fibroblasts) are eliminated from engineered tissue constructs, then tissue functional stability is improved, but the ability to control temporal organogenesis and expansion deteriorates
Solution Approach 1:
The patent applies dynamics by making the cell population composition dynamic rather than static. Inducible genetic constructs (e.g., tetragen, Cre-lox) allow supporting cell elimination to be triggered at specific time points during tissue development. This temporal control enables the tissue to adapt its cell composition dynamically: maintaining supporting cells during early organogenesis for structural support, then eliminating them later to stabilize tissue function and prevent fibrosis.
Solution Approach 2:
The patent implements preliminary action by pre-engineering the tissue construct with inducible genetic constructs before supporting cell elimination. These constructs (e.g., fibroblasts expressing inducible caspase-9 or Cre-recombinase) are prepared in advance with the molecular machinery needed for controlled elimination. When triggered by small molecules (doxycycline, rapamycin) or inducers (tamoxifen), the pre-installed systems enable rapid and selective supporting cell removal without requiring new genetic modifications at the time of elimination.
2Ease of operation
If inducible genetic constructs are used to control cell death, then selective elimination of supporting cells is improved, but device complexity increases
Solution Approach 1:
The patent applies taking out by extracting the control mechanism from the bulk tissue and concentrating it in specific supporting cell populations. Inducible genetic constructs are selectively introduced into fibroblasts or other supporting cells, while parenchymal cells remain unaffected. This selective targeting allows precise spatial and temporal control: when triggered, only the engineered supporting cells undergo apoptosis or differentiation changes, leaving the functional parenchymal cells intact and preserving tissue-specific functions.
Solution Approach 2:
The patent uses intermediary molecules to bridge the control system and the cell death mechanism. Small molecules (doxycycline, rapamycin, tamoxifen) serve as intermediaries that bind to inducible elements (tet-operator, FKBP-FRB, estrogen receptor) in the genetic constructs. These intermediaries translate external chemical signals into intracellular responses: doxycycline activates tetracycline-controlled transcription, rapamycin induces FKBP-FRB dimerization triggering caspase-9 activation, and tamoxifen activates Cre-recombinase. This intermediary layer provides precise temporal control while simplifying the operation to simple molecule addition.
3Productivity
If parenchymal cell function is maintained during supporting cell elimination, then tissue secretory function is improved, but tissue integration and vascularization deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the tissue construct into functionally distinct cell populations with different genetic engineering statuses. Parenchymal cells (hepatocytes, pancreatic cells, cardiomyocytes) are left unengineered and maintain their native functions, while supporting cells (fibroblasts, stromal cells) are selectively engineered with inducible constructs. This segmentation allows independent control: parenchymal cells continue producing secretory products (albumin, insulin, contractile function) while engineered supporting cells can be eliminated or modulated to improve tissue integration and vascularization without compromising secretory productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the temporal control of tissue organogenesis and expansion, allowing for the elimination of unnecessary cell populations without disrupting the function of parenchymal cells and enhancing secretory functions like albumin secretion, while promoting vascularization and tissue integration.
Implementation Method 1
activated by chemical inducers of dimerization
Implementation Method 2
controlled expression of cell death-inducing polypeptides or nucleic acids, such as caspase 9
Data Source
AI summary
Inducible engineered tissue constructs comprising at least one cell population comprising a genetic construct are provided. Methods of making and using said constructs are also provided.