yes it is possible.

However you have to know that healthy donors have relatively low amount of cell free circulating DNA. Also the DNA you obtain will be very fragmented. 

It has been used to detect down syndrome during pregnancy via non invasive test.

It is also used in cancer patients (who are known to have high amount of circulating DNA) for predictive and prognostic markers screening.

You have several kits from diverse companies to extract the circulating DNA. I  personally use the Qiagen which works fine.

good luck

Article DNA sequencing of maternal plasma to detect Down syndrome: A...

Article Liquid biopsy: Monitoring cancer-genetics in the blood

yes it is possible.

However you have to know that healthy donors have relatively low amount of cell free circulating DNA. Also the DNA you obtain will be very fragmented. 

It has been used to detect down syndrome during pregnancy via non invasive test.

It is also used in cancer patients (who are known to have high amount of circulating DNA) for predictive and prognostic markers screening.

You have several kits from diverse companies to extract the circulating DNA. I  personally use the Qiagen which works fine.

good luck

Article DNA sequencing of maternal plasma to detect Down syndrome: A...

Article Liquid biopsy: Monitoring cancer-genetics in the blood

• Yes, Human circulating DNA coming from dying cells is found in Plasma and can be extracted. I think one would require upto an ml or two to extract any significant amounts for PCR and such. Circulating DNA as pointed out, is highly fragments and PCR designs for detections of genes should be in the range of 100-200bp - never larger. Lastly, in disease conditions and after surgery/transplantation there is a huge spike in circulating DNA. 

of course!  Many kits are available in the market with  well described protocols

yes, you can 

I have extracted DNA from long term freeze plasma. Although I can obtain human DNA, yields are very low (  approx. 1-4 ng/ul).  

Methee Sriprapun, recently I have extracted DNA from healthy plasma of human, but I have no idea simple methods to quantify this DNA (except real-time PCR). Could you show me the method you used, please?

Ngan Nguyen,

You may be able to use ThermoFisher's NanoDrop One/Oneᶜ - it can detect 0.2–27,500

ng/μL for dsDNA.

I started with 500ul plasma samples from healthy individuals and used Qiagen mini blood kit. Got about 1-4ng/ul in 100ul elute (nonodrop). I am going to check the quality on tapestation next.

Thank you for your reply, George Tollefson. But we don't have this machine in our lab. Is there any other method? 

Ngan, you can use spectrophotometry by measuring absorbance at 260nm using a spectrophotometer. It is simple to do and is consistent. However there are several limitations to this method. It is not specific for double stranded DNA - RNA and free nucleotides will be counted also, resulting in falsely high quantification readings. Also, It is not specific to human DNA, so if DNA from other species has contaminated your plasma sample it could result in a falsely high quantification reading.

Alternately, you can look into slot blot or picogreen methods.

Good luck!!

Thank you so much, George Tollefson, I will try it.

Hi Ngan Nguyen,

While I agree with George Tollefson that spectrophotometer is a good method for DNA quantification, it might be impaired by the low quantity obtained from plasma DNA extraction.

I would say that the gold standard to quantify circulating DNA are:

- Fluorescent quantification via Qubit or Picogreen.

- Bioanalyser 

- real time PCR.

Classical spectrophotometer and nanodrop are usually not sensitive enough unfortunately.

Moreover depdending on the extraction kit you use, they might be impaired by carry over (e.g. RNA carrier from the Qiagen kit, ethanol...).

I would say that, as good practice, you should look at the nanodrop profile for carryover identification but not for quantification.

I hope it helps,

Best,

Ludovic

Hi, Ludovic Barault

I saw many protocols suggest to isolate plasma by a two-round centrifugation, first using a low-speed centrifugation at 1300-1600g for 10 min to remove blood leukocytes, and then followed by an alternative step using a high-speed centrifugation at 12-16,000xg to remove additional cellular nucleic acids attached to cell debris.  So I was wondering whether my stored plasma that isolated only by a low-speed centrifugation are suitable for cfDNA isolation. What's your opinion? Thanks!

Best,

Wanhai

Hi Wanhai,

In my laboratory we use a 2 step centrifugation. 10 min 1600g and 10min 3000g.

I did not participate in the optimization of this part of the protocol, therefore I can not really discuss about the reason of using 3000 instead of 10000g for the second centrifugation.

What I can tell is that after the second centrifugation you still have cell debris visible at the bottom of your tubes.

I am sure you can get ccfdna from one step centrifugation, however it might be more contaminated by DNA from leukocytes.

So depending on the technique you will use after, this might be a problem.

If you just have a ultra sensitive technique for which the output is qualitative (presence or absence),I would expect you to be fine.

If instead your technique is not that sensitive and rely on quantification, such samples might be troublesome.

I hope it helps,

best

Ludovic

Yes you can isolate DNA from human blood plasma, which is also known as circulating cell-free DNA.

But the point is, which method will u prefer conventional Triton/Heat/Phenol protocol(THP) or kit based method?

Hi Ludovic ,

Thanks for your reply. I am planing to isolate plasma DNA to meassure DNA methlation, since the plasma were isolated a long time agao, so I warryed about the blood leukocytes DNA contamination. Do you think if I do the high speed centrifugation after thrawing my sample will reduce this risk of Leukocytes DNA contamination?

Best,

Wanhai

Hi Wanhai,

We're in fact doing a 5 minutes

At 16,000 g centrifugation post thawing, and prior to the extraction.

Though I'm not sure it really decrease the leukocyte DNA contamination.

Another thing you want to consider if your samples are old is the temperature at which they were maintained. You really need to be at -80℃, storage at -20℃ is clearly not enough to maintain proper integrity of the ccfdna. Also if the samples were subjected to multiple freezing thawing cycles, the few ccfdna might have been degraded.

I hope it helps,

Good luck

Hello, I'm doing viral loads of cmv with a tib molbiol kit. Apparently I have problems in the extraction with the MagnaPure. 400ul of EDTA plasma is taken and eluted in 50uL of which I obtain from 0.05-0.9 mg / mL and the results of the viral load are different from those obtained in cobas 4800. In addition, the results of the control show a much higher Ct ( 28-38) than those of the kit insert for 10E6 leukocytes showing a ct of 25-26. What is the amount of DNA that I could get from the plasma? Could it be that the problem is extraction? Thanks for your help

hi..is there any procedure to extract cell free DNA from plasma WITHOUT kit?