A Rapid Seeding Technique for the Assembly of Large Cell/Scaffold Composite Constructs

These studies address critical technical issues involved in creating human mesenchymal stem cell (hMSC)/ scaffold implants for cartilage repair. These issues include obtaining a high cell density and uniform spatial cell distribution within the scaffold, factors that are critical in the initiation and homogeneity of chondrogenic differentiation. For any given scaffold, the initial seeding influences cell density, retention, and spatial distribution within the scaffold, which eventually will affect the function of the construct. Here, we discuss the development of a vacuum-aided seeding technique for HYAFF^®-11 sponges which we compared to passive infiltration. Our results show that, under the conditions tested, hMSCs were quantitatively and homogeneously loaded into the scaffolds with 90+% retention rates after 24 h in perfusion culture with no negative effect on cell viability or chondrogenic potential. The retention rates of the vacuum-seeded constructs were at least 2 times greater than those of passively seeded constructs at 72 h. Histomorphometric analysis revealed that the core of the vacuum-seeded constructs contained 240% more cells than the core of passively infiltrated scaffolds. The vacuum seeding technique is safe, rapid, reproducible, and results in controlled quantitative cell loading, high retention, and uniform distribution.