Engineering ligament tissues: Synergistic power of aligned nanofibers and cyclic stretch

Table 1 Preclinical and clinical development plan for a ligament tissue engineering scaffold

Stage	Model & actions	Key assessments	Regulatory milestones
Small-animal studies	Rat ACL defect model GLP-compliant protocols	Immune: ISO 10993 cytokine panels; histology for inflammation. Degradation: In vivo micro-CT scaffold mass loss. Mechanics: Uniaxial tensile tests at weeks 4, 8, 12	Pre-IND meeting with FDA
Large-animal validation	Sheep or goat ACL repair model	Immune: Serum CRP & IL-10; synovial fluid analysis. Vascular: MRI/ultrasound neovascularization. Mechanics: Cyclic fatigue of explants; gait analysis	IDE submission; ISO 10993 certification
Regulatory submission	Compile preclinical dossier CMC documentation (PLA formulation, fabrication controls)	Data aggregation: Safety, efficacy, reproducibility	IND filing (FDA) or CTD submission (EMA)
Phase I trial	Small human cohort	Immune: Serum cytokines; biopsy histopathology. Mechanics: Instrumented laxity testing; MRI	IRB approval; informed consent protocols
Phase II trial	Scaffold dose/size optimization; preliminary efficacy	Function: KT-1000 arthrometer; IKDC & Tegner scores. Degradation: MRI at months 3, 6, 12	Interim safety reviews; DSMB oversight
Phase III trial	Large-scale efficacy and long-term safety	Biomechanics: Contralateral leg control; return-to-activity metrics. Integration: Second-look arthroscopy; histological biopsy	PMA submission (FDA) or CE marking application

ACL: Anterior cruciate ligament; GLP: Good laboratory practice; CT: Computed tomography; IND: Investigational New Drug; FDA: Food and Drug Administration; CRP: C-reactive protein; IL-10: Interleukin-10; MRI: Magnetic resonance imaging; IDE: Investigational device exemption; CMC: Chemistry, Manufacturing, and Controls; PLA: Poly-lactic acid; CTD: Common technical document; EMA: European Medicines Agency; IRB: Institutional Review Board; IKDC: International Knee Documentation Committee Subjective Knee Form; DSMB: Data and Safety Monitoring Board; PMA: Pre-market approval.