Conditions affecting cell seeding onto three-dimensional scaffolds for cellular-based biodegradable implants

Seeding cells efficiently and uniformly onto three-dimensional scaffolds is a key element for engineering tissues, particularly when only a low-number of cells is available for tissue repair and regeneration. The aim of this study was to evaluate three seeding techniques on two biocompatible scaffolds in vitro using chondrocytes as follows: (1) static; (2) modified centrifugal cell immobilization (CCI); and (3) dynamic oscillating motion. Five milliliters of media containing 5, 10, or 25 million articular, auricular, or costal chondrocytes were used to seed porous PLGA scaffolds and sections of devitalized cartilage. The dynamic oscillating technique resulted in up to 150% higher cellular load at 7 days than CCI seeding. Cell distribution was more homogeneous throughout the scaffold under dynamic conditions versus more sporadic and dispersed cell concentrations on the scaffolds when using either the static or the modified CCI technique. Cell load and distribution, when using a low numbers of chondrocytes at one and two million cells per milliliter, was comparable to that using the much higher number, especially under dynamic seeding conditions. The seeded scaffolds were used as implants to achieve cellular bonding between two devitalized meniscus discs. The constructs were implanted subcutaneously in nude mice for 12 weeks and analyzed histologically. Implants seeded with auricular chondrocytes showed qualitative more integration into native meniscus tissue than articular and costal cell implants. We conclude the dynamic oscillating seeding technique is an efficient technique for seeding low-cell numbers onto scaffolds resulting in consistent and uniform cell distribution throughout porous PLGA scaffolds.