Whole ovine caudal intervertebral discs (IVD) were cultured in sufficient and limited nutrition
under simulated-physiologic loading for 7 and 21 days.
To study the effect of limited nutrition
on disc cells embedded in their native tissue in short- and midterm whole organ disc culture.
Summary of Background Data.
Nutrient-limited induction of disc cell death in vitro
has been demonstrated and is believed to be a factor in disc degeneration. Nutrient-limited cell death and its consequences, as it relates to degeneration, have not been investigated in the intact IVD.
Ovine IVDs with endplates were cultured for 7 and 21 days under simulated-physiologic loading, either in media with limited (2 g/L) or sufficient (4.5 g/L) glucose
concentration. Cell viability
, relative gene expression, newly synthesized chondroitin sulfate content, and matrix metalloproteinase (MMP) activity were measured after culture and compared to fresh tissue.
In sufficient glucose
media, cell viability
was maintained through 7 days to 21 days of culture. In limited glucose
, it dropped significantly to 62% in the anulus fibrosus and to 56% in the nucleus pulposus after 7 days and remained so until 21 days (63% in the anulus fibrosus and 52% in the nucleus pulposus). No significant differences were found between culture conditions for relative gene expression, newly synthesized chondroitin sulfate and inactive and active forms of MMP13 and MMP7.
With this culture system, whole IVD explants could be maintained up to 21 days. Cell viability
decreased to 50% to 60% under limited nutrition
within days and remained so up to 3 weeks. The surviving cells did not compensate matrix production in this time frame.