A combination of shear and dynamic compression leads to mechanically induced chondrogenesis of human mesenchymal stem cells.
The device is basically a ball placed directly on the mesenchymal stem cells. I assume to be like the ball of the knee joint. So the purpose of the ball was for it to oscillate to generate fluid shear strain.
"Group A was the free-swelling (unloaded) control. Group B was exposed to unconﬁned dynamic compression at 1 Hz with 0.4 mm sinusoidal strain, superimposed on a 0.4 mm static offset strain, resulting in a strain amplitude of 10-20 % of the scaffold height at the centre of the construct. Group C was exposed to ball oscillation of ±25° at 1 Hz, superimposed on a 0.4 mm static compression offset strain. Group D was a combination of both loading regimes. Mechanical load was applied during 1 h a day for 5 consecutive days per week over 3 weeks"<-LSJL loading applies load for slightly over 1 minute which is much less than 1 hour.
"There was a trend towards higher total GAG/DNA values in the loaded groups which included shear[so shear strain is very important for inducing chondrogenesis, axial loading induces no shear strain thus no chondrogenesis], but no signiﬁcant difference over the compression only group was detected. All individual donors demonstrated the same trend[so all individual bone marrow sources were capable of chondrogenesis]"
Compression and Sox9 groups expressed much more Sox9 than just shear groups alone. So compressive forces are still important to chondrogenesis. If you look at Figure 6D in the study you can almost see a growth plate.
What we can take from this study is that maybe the LSJL clamping routine is not dynamic enough at inducing fluid based shear strain. Perhaps rapid clamping and unclamping would be a way to make LSJL induce more shear forces.
The ball device is not something that could be used as you'd need to put the ball directly against the bone marrow. Maybe surgically implanting a ball in the bone marrow may be a possibility for the future.