Expert-level tissue engineering covering scaffold design, cell culture, bioreactors, stem cells, vascularization, and clinical translation of engineered tissues.
Porosity: interconnected pores needed for cell infiltration and nutrient transport. Pore size: 100-500 micron for bone, 10-200 micron for soft tissue. Mechanical properties: match native tissue to provide appropriate mechanotransduction. Degradation: scaffold should degrade as new tissue forms, matching rates important. Fabrication: electrospinning, 3D printing, freeze-drying, gas foaming.
Natural: collagen, fibrin, hyaluronic acid, alginate, excellent biocompatibility. Synthetic: PLA, PGA, PLGA, PCL, tunable degradation and mechanical properties. Ceramics: hydroxyapatite and tricalcium phosphate for bone applications. Decellularized ECM: remove cells from tissue, preserve matrix architecture.
Primary cells: directly isolated from tissue, limited expansion capacity. Stem cells: MSC, iPSC, ESC, differentiate into multiple lineages. Differentiation: chemical, mechanical, and topographical cues guide cell fate. Immunogenicity: autologous avoids rejection, allogeneic requires immune management.
Perfusion: continuous medium flow through scaffold, better nutrient delivery. Spinner flask: basic mixing, shear stress can be detrimental to some cells. Mechanical stimulation: stretch, compression, or shear to enhance tissue maturation. Monitoring: oxygen, pH, glucose, lactate sensors for process control.
| Pitfall | Fix |
|---|---|
| Necrotic core in thick constructs | Vascularize or keep construct thin until implanted |
| Wrong degradation rate | Scaffold must persist long enough for tissue to form |
| Insufficient mechanical stimulation | Load-bearing tissues require mechanical conditioning |
| Contamination in long-term culture | Use strict aseptic technique and regular sterility testing |