Evaluation Of The Biocompatibility Of Degradable Material PLLA-PEG Polymer And The Control-release Behavial Of The ADM-loaded Polymer In Vitro

There are two kinds of Liver cancers, primary liver cancer andsecondary liver cancer. It is considered that the incidence of primaryliver cancer is rising per year whether in the east or in the west. Andliver is also an organ contains a lot of metastatic cancers. Up to now,liver cancers have been one of the most common malignant tumorsdo harm to humen body. The therapeutic regimen of liver cancer for now is a kind ofcombined therapy based on surgical intervention. And chemotherapyafter liver cancer resections is an inseparable part in the therapyregimen. But most antitumor drugs have a thin safe range and a shortdemiperiod, so routine methods of administrations have theirlimitations such as need more drugs and more times of injection (orother methods) to maintain blood drug level, and difficult to controlthe blood drug concentration in the safe and effective range. Whiletheoretically, a controlled or sustained drug delivery system will behelpful for this. Implantable Drug Delivery Systems (IDDS) is a kind of thedrug delivery systems. We plant an antitumor drug loadedbiomaterial which can release the drug persistently into the positionswhere the tumors occur in the patients, so that the drug can maintainan effective level in local position of the tumors while the blood druglevel is in the safe range.PLLA-PEG polymer is a kind of degradable macromoleculebiomaterials invented by Changchun Institute of Applied ChemistryChinese Academy of Sciences (ciac). It is a compound of PLLA andPEG. The lipophilicity of PLLA and the hydrophilicity of PEG makethe polymer PLLA-PEG have an amphipathicity. So it can carrydrugs both oleophylic (such as toxel) and hydrophilous (such asdoxorubicin). The more important thing is that PLLA and PEG areboth degradable. And the end products of them are CO2 and H2O. So,the polymer is considered to be the very biomaterial we looking for.Before used in clinic, biomaterials must be accessed to be withacceptable biocompatibility (safety and efficacy). There are twomethods to test the biocompatibility of a biomaterial: in vitro and invivo. An in vivo test is much more expensive time-costing anddifficult to control the effective factors than an in vitro one. And anin vivo test will be limited by ethics and morality, too. So we oftenchoose an in vitro one to take the place of an in vivo one when wewant to evaluate a biomaterial at the primary stage.Therefore, in this study we used the in vitro test to evaluate thebiocompatibility of the degradable biomaterial PLLA-PEG polymer.There are three parts in this test: 1.The evaluation of cytotoxicity ofPLLA-PEG polymer. We adopted the leaching liquor of PLLA-PEGpolymer to interact with L929 mouse fibroblast cells, and performMTT test to detect the cell inhibition ratio on the next day and thethird day after the interaction. And then assess cytotoxicity of thebiomaterial. Meanwhile, we perform an FCM to analysis the cell cycleof L929. 2.The drug release test of the polymer. In this part, we put theADM-loaded PLLA-PEG polymer into the RPMI1640 culturemedium and take samples at different time. We detect the OD of thesamples with a spectrophotometer and count the accumulated drugconcentrations with the ODs. And then we obtained the drug deliverycurve. 3. Contraction of SMMC-7721 human liver cancer cellinhibitions between ADM-loaded PLLA-PEG polymer and pure ADMin the same dosage. Both groups have their controls. For example, weused blank PLLA-PEG polymer as the control of the experimentalgroup (ADM-loaded PLLA-PEG polymer group), and the pure ADMgroup, we used RPMI1640 culture medium. We take samples toperform MTT tests at the 6th hour and 1st day, 2nd day, 3rd day, 4th day,5th day, 6th day, 7th day after they interact with SMMC-7721 cells.With the cell inhibitions obtained from MTT tests to contract. Andalso, we perform FCM to analysis the cell cycle of SMMC-7721.In the first part, we found that only the 6cm2/ml (surface area ofpolymer/solvent) 100% group has a cytotoxicity of level 2, whileother groups such as 50%, 25% and all 0.5cm2/ml (surface area ofpolymer/solvent) groups have a cytotoxicity of level 1. The results ofFCM indicate that the polymer has no effects on cell cycle of L929.All results above mean that the biomaterial is acceptable in clinic. Inthe second part, the result is that the 2.0wt% group has a suddenrelease (maybe caused by the different artwork) while the 1.5wt%group hasn't. So the 1.5wt% group matches our requirement. And wecontinue our study with the 1.5wt% group in the coming step. In thethird part, we found that the ADM-loaded PLLA-PEG polymer grouphas a more effective and longer cell inhibition than the pure ADMgroup (maybe because the ADM-loaded PLLA-PEG polymer grouphas a high drug level in the local place where SMMC-7721 cellsgrow). The result was anticipated. And the results of FCM proved thatthere are no effects on the antitumor drug (ADM) to antitumorefficiency.In summary, we can conclude that the degradable biomaterialPLLA-PEG polymer invented and produced by CIAC has anacceptable biocompatibility in vitro. As a sustained drug deliverycarrier, it can release ADM stably. And so the loaded drug (ADM) canmaintain a stable level to play its role on antitumor. This make ADMhas its better and longer effect on SMMC-7721 human liver cancercells than the pure ADM group at the same dosage. All of theseprimarily prove that we use an implantable drug delivery system inlocal position to combine with excision to deal with malignant tumor(such as liver cancer) is safe, effective and feasible. And we obtainedthe theory foundation and numerical data for the next step study invivo, too.Objective: To Evaluate the biocompatibility of degradablematerial PLLA-PEG polymer and the control-release behavial of theADM loaded polymer compounds in vitro.Methods: The L929 cells and SMMC-7721 cells used in theexperiment were cultured in vitro,and the MTT assay was used toexaminethe antiproliferative effect of PLLA-PEG polymer on L929cells and ADM-loaded PLLA-PEG polymer on SMMC-7721;FCMwas used to examine the effects of pure PLLA-PEG on L929 andADM-loaded PLLA-PEG polymer and free ADM on the cell cycle ofSMMC-7721 cells.Results:1) The 6cm2/ml (surface area of polymer/solvent) 100%group has a cytotoxicity of level 2, while other groups such as 50%,25% and all 0.5cm2/ml (surface area of polymer/solvent) groups havea cytotoxicity of level 1. The results of FCM indicate that the polymerhas no effects on cell cycle of L929.2) the 2.0wt% group has a sudden release (maybe caused by thedifferent artwork) while the 1.5wt% group hasn't.3) the ADM-loaded PLLA-PEG polymer group has a moreeffective and longer cell inhibition than the pure ADM group (maybebecause the ADM-loaded PLLA-PEG polymer group has a high druglevel in the local place where SMMC-7721 cells grow) which wasanticipated. And the results of FCM proved that there are no effects onthe antitumor drug (ADM) to antitumor efficiency.Conclusion: PLLA-PEG polymer has a good biocompatibility invitro, and the ADM-loaded PLLA-PEG polymer can inhibit thegrowth of SMMC-7721 cells longer than the same dose free ADM.