I tried switching HUVECs from EGM-2 media to M-199, 20%FBS, sodium bicarbonate and HEPES and they did not grow at all. So I do not recommend using M-199 unless you are going to supplement the media with growth factors (i.e FGF, VEGF, etc). I did not try that though.

Good Luck!

Thank you Tom. I'll add 30ul FGF and give a try may be with one vial. 

I agree with Tom. According to my experience working with HUVECs and EPCs, I recommend you not change the growth medium provided from Lonza. I would like to share with you some experiences. Firstly, I used HUVECs gifted from a laboratory. In this occasion, the growth medium was Medium199 supplemented with 20% FCS or FBS, 1% Penicillin/Streptomycin, 0.05% Heparin and finally 5% endothelial cell growth supplement (ECGS). In contrast, we bought a vial HUVECs passage 1 (Lonza), which was cultured in EGM-2 according to manufacturer's instructions. We tried to culture them in the first medium since it is cheaper, but we had problems with the proliferation as mentioned by Tom. In conclusion, it is very important to use the same medium which was used also in the isolation process (passage 1). It is kown that, the cells in early passages and especially 1 are very sensitive, thus every change will affect their growth and proliferation. From my opinion, continue to work with EGM-2 until passage 3 and then check after splitting to use Medium199 in a plate. The cells should be acclimatized to the new medium. In contrast, using Medium199 in passage 1, the cells may be stressed since they are not used to this medium.

I hope that I helped you with my advice!! Good luck!!

Thank you Vasileios. Same thing happened to me, I got the HUVEC as a gift from other lab (passage 4), I just needed that for may be 2/3 experiments, so it didn't really bothered me. But now we are planning to go further with HUVEC, thus looking for something cheaper. Anyway, we will buy HUVEC from Lonza and the media as well. 

Thank you again.