It is 1.5 cm2 electrospun scaffold. My point is the cell number in in vitro condition and in vivo condition promoting growth and differentiation will be same or different . Is the population doubling time in vitro as well as in vivo will be same? since in vivo encounter many factors including the immune system.

HI Sunitha,

What is your animal and injury model? The in vivo situation will indeed be different from what you observe in vitro. I use porous scaffolds measuring 8 x 3 x 2 mm; for in vitro I seed only 100k cells (MSCs), but for in vivo (in a rat model) I seed 1 million cells. You should check literature and how many cells people have used for your injury model.

Thanks for your reply. I would like to know what point made you to seed 10 times more cells on scaffold when you already show the 100k seeding will work with your biomaterial? At the same time we seed nearly 10% of cells in a T25 flask for maintenance. So the 100k in this small area will make the cells to form monolayer by next day itself. I have seen the same scenario in many papers they have loaded with high number of cells. I could not find any where any explanation for this.Adherence and cell proliferation is compromised while the cells growing on scaffold. this is the answer. i always give. can you suggest some other reason too.

We did an earlier study where we observed a dose response relationship between number of cells and the functional recovery after an injury. Using a low cell number might not have a great influence on healing, esp in vivo, so you have to use high cell numbers. Secondly your electrospun scaffolds are 3D and porous, so they can accomodate more cells than a 2D culture plate. And since porous scaffolds have a higher surface area, there is more space for the cells to attach and grow.

Thank you.i totally agree with you.

I agree that greater cell numbers are needed for in vivo applications than in vitro. When cells are implanted in vivo, a significant portion (I believe over 75%) of implanted cells will die, so the larger cell number allows for a greater population on the scaffold than a lower cell number that might be suitable for in vitro.