How to Use
- What solvent should be used to dissolve the PG peptides? Is it soluble in anything other than DMSO?
It is soluble in general media, but in the case of ultra-trace amounts, such as 2㎍, the PG peptide in medium may adhere to the container and micropipette tip, we recommend to use DMSO for solubilization.
- How stable is PG peptide in the medium compared to conventional growth factors?
All PG peptides have been confirmed to be stable in advanced DMEM/F12 medium(w/o serum) at 37℃ for at least 1 week.
- What is the degree of residuals in the cell and in the final product?
PG peptides do not directly enter the cells. Therefore, the amount of PG peptide remaining in the final product is expected to be reduced to below the detection limit by medium exchange and washing.
On the other hand, it is theoretically possible for PG peptides to enter cells by endocytosis and undergo proliferation and differentiation while still bound to the receptor, therefore we cannot guarantee that the residual amount of PG peptides will be completely zero. Since the residual amount of PG peptides is greatly affected by conditions such as the concentration used in the actual process and the washing operations, it is desirable to evaluate the residual of PG peptides in each product.
We can conduct a contract analysis of the residual amount of PG peptide in the final product by ultra-sensitive MS, etc. Please contact us for more information.
- Do PG peptides have toxicity?
Toxicity tests using cultured cells were conducted during the development phase, and it was confirmed that there was no toxicity even at 10 μM, the maximum concentration in the tested range.This concentration is more than 1000 times higher than the concentration range at which most growth factors are active, and is therefore considered non-toxic under normal conditions of use.
More detailed toxicity data for the PG peptide is currently being obtained and will be shared.
- What are the stability and storage conditions of PG peptides?
The PG peptides should be stored at -20°C. Although we set the shelf life of our products as 2 years, we are obtaining more stability data showing that the PG peptides are stable under higher temperatures than -20°C for more long time than 2 years. Also we are evaluating the stability of PG peptides in culture media. Please contact us for more information.
- What is the endotoxin content of PG peptides for research use only?
Endotoxin testing is not performed on PG peptides for RUO, but we can conduct Endotoxin testing on GMP products of PG peptides upon request.
- Is it possible to visually confirm the presence of PG peptide in the container?
Unfortunately, visual confirmation of PG peptide is difficult due to the ultra-trace amount, such as 2 μg.
- The prices of PG peptides seem high.
PWe adjusted the activity of PG peptides to the same level of activity per "molar concentration"(not in the unit of ng/mL or pg/mL) of the recombinant growth factors. As the molecualr weights of PG peptides are much smaller than that of corresponding growth factors, for example, PG-001 has 1/16th of the molecular weight of the HGF. Therefore, 2 μg of PG-001 is equivalent to 32 μg of HGF and the prices of PG peptides are set at such equivalent amounts of growth factors.
- Is there a difference in activity per molar concentration between "PG peptides" and "recombinant growth factors?"
For all PG peptides, the activity per mole concentration is adjusted to the same level of corresponding growth factors.
- Do PG peptides act on different targets (off-targets) ?
Off-target panel testing was conducted during the development phase of all PG peptides to evaluate the presence or absence of off-target activity against 68 different targets. PG-001 to 003 did not show significant off-target activity at 5 to 10 μM.
On the other hand, PG-004 showed inhibitory activity (64%) against glucocorticoids at 10 μM, but PG-004 did not show off-target activity against other 67 targets. Therefore, we believe that there is almost no off-target activity of PG-001~004 at the concentrations normally used (pM~nM ranges).
- Is it OK to assume that PG peptides and recombinant growth factors have the same mechanism of action?
PG peptides work in the same mechanism of action as recombinant growth factors and we have confirmed that they show the same activity as growth factors in cell proliferation and differentiation behavior of cultured cells. However, some growth factors exhibit weak binding to other receptors in addition to their main receptors with strong affinity. Such complex binding behabiors of growth factos may be difficult to reproduce with PG peptides because PG peptides have very high specificity. Therefore, the possibility that growth factors and PG peptides have potentially different physiological activities cannot be completely ruled out.
- Can PG peptides enter the cell?
PG peptides are not permeable to cell membrane. However, there is a possibility that PG peptides may temporarily enter cells via endocytosis or other means while bound to receptors. We are currently obtaining the residual properties of PG peptides. Please also refer to our response to Properties Q2.
- Will the PG peptide continue to remain on the receptors on the cell membrane?
It depends on the purification method of the final cellular product, but basically we believe that all PG peptides will be washed out during washing and purification processes. Please also refer th the answer to Properties Q2.
- How safe are PG peptides?
We conducted toxicity assay of PG peptides using cultured cells and confirmed that there is no toxicity. Pelase also see the answer to Properties Q3.
- Any in vivo testing fo PG peptides to ensure safety?
We haven't conducted in vivo testing of PG peptides yet. So far we only have in vitro cytotoxicity data using cultured cells, showing no toxicity upto 10 μM of PG peptides, which is more than 1000 times the biologically active concentration of PG peptides. We will share the results of the in vivo study of PG peptides in the future when they become available.
- What are the quality control methods for PG peptides after production?
Each lot of PG peptides is tested for purity (≧95%) by LC/MS and activity evaluation using cultured cells.
- Quality control on sterility of PG peptides after lyophilization.
After sterilization by filter filtration in DMSO solution, the PG peptides are sterilely portioned, freeze-dried, and sealed to ensure sterility. Sterility testing is not performed on the sealed product. However, we conducted activity test of each lot of PG peptides after lyophilization using cell-based assay and we observed no contamination during culturing cells with PG peptides, assuring the sterility of PG peptides after lyophilization.
- How stable are PG peptides?
A long-term stability tests on PG peptides are in progress now.The storage tests of lyophilized PG-001 and PG-002 at -20℃ have been completed for 1 year so far and we confirmed no decrease of purity of PG-001 and PG-002.
We will update the long-term stability data of PG peptides in the future. In addition, we evaluated the stabitily of PG peptides in cell culture medium(advanced DMEM/F-12 w/o serum) at 37℃ and confirmed all PG peptides are stable at least for 1 week.
- Is it possible to manufacture under GMP?
It is possible for a contract manufacturing company (e.g., PeptiStar) to manage manufacturing in accordance with GMP control standards.
- Is it possible to issue an certificates of Animal Origin Free(AOF)?
- What are the shipping conditions/forms of PG peptides?
We ship PG peptides at -20℃.PG peptides are provided as lyophilized products without any additives. All PG peptides are in acetate salt form.