Non-flammable preparative reversed-phase liquid chromatography of recombinant human insulin-like growth factor-I

Use of mobile phase additives for the elution of bispecific and monoclonal antibodies from phenyl based hydrophobic interaction chromatography resins

Hydrophobic interaction chromatography (HIC) is routinely used in the purification of biopharmaceuticals such as antibodies. However, hydrophobic proteins can be difficult to elute resulting in low recovery of product thereby complicating early phase process development and potentially excluding the use of HIC resins for their manufacture. Mobile phase additives such as hexylene glycol and arginine facilitate protein elution from resins including HIC; therefore, these additives were evaluated toward the recovery and purification of bispecific and monoclonal antibodies from Phenyl Sepharose HP and Capto Phenyl ImpRes resins. The influences of gradient versus step elution as well as superficial linear velocity on product quality were evaluated. Improved protein recovery and reduction of both soluble product aggregate and host cell protein were observed for the tested antibodies with both hexylene glycol and arginine. Furthermore, the impact of salt removal from the HIC load on protein-resin binding was examined providing opportunities to minimize processing time. This method was successfully scaled using a Phenyl Sepharose HP (5 cm i.d. × 20.0 cm) and Capto Phenyl ImpRes (3.2 cm i.d. × 21.4 cm) column demonstrating potential for manufacturing purposes.

Injectable hyaluronic acid microhydrogels for controlled release formulation of erythropoietin

An injectable hyaluronic acid (HA) microhydrogel was successfully developed as a novel drug carrier for controlled release formulation of protein drugs. HA hydrogels were prepared by the disulfide bond formation of thiolated HA (HA-SH). EPO was loaded in situ during HA-SH hydrogel preparation using an accelerating agent of sodium tetrathionate. The gelation time was drastically reduced from a day to 30 min when sodium tetrathionate was added for HA-SH hydrogel preparation. In vitro release of EPO in PBS at 37 degrees C showed that EPO was rapidly released for 3 days with an initial burst and then slowly up to 9 days from HA-SH hydrogels. HA-SH microhydrogels were prepared by the reactive spray drying of diluted HA-SH precursor solution. The mean particle size was approximately 2.3 mum and the water content after spray drying was approximately 14%. Ellman's test showed that sodium tetrathionate contributed not only for rapid crosslinking reaction but also for the reduction of residual free thiol content in HA-SH microhydrogels after spray drying. EPO recovery from HA-SH microhydrogels after degradation with hyaluronidase SD was higher than 95%. The released EPO appeared to be intact from the analysis with RP-HPLC. According to in vivo release test of EPO from HA-SH microhydrogels in Sprague Dawley (SD) rats, elevated plasma concentration of EPO higher than 0.1 ng/mL, which is a critical minimal concentration for EPO efficacy, was maintained up to 7 days. There was no adverse effect during and after the in vivo tests.

Sustained release formulation of erythropoietin using hyaluronic acid hydrogels crosslinked by Michael addition

A novel sustained release formulation of erythropoietin (EPO) was successfully developed using hyaluronic acid (HA) hydrogels crosslinked by Michael addition. Adipic acid dihydrazide grafted HA (HA-ADH) was prepared and then modified into methacrylated HA (HA-MA). (1)H NMR analysis showed that the degrees of HA-ADH and HA-MA modification were 69 and 29 mol%, respectively. Using the specific crosslinkers of dithiothreitol (DTT) and peptide linker, EPO was loaded during HA-MA hydrogel preparation by Michael addition chemistry between thiol and methacrylate groups. The amount of EPO recovered from both hydrogels after degradation with hyaluronidase SD (HAse SD) was about 90%. The crosslinking reaction with peptide linker (GCYKNRDCG) was faster than that with DTT. The gelation time was about 30 min for peptide linker and 180 min for DTT. In vitro release test of EPO from HA-MA hydrogel at 37 degrees C showed that EPO was released rapidly for 2 days and then slowly up to 7 days from HA-MA hydrogels. The released EPO appeared to be intact from the analysis with RP-HPLC. According to in vivo release test of EPO from HA-MA hydrogels crosslinked with the peptide linker in Sprague-Dawley (SD) rats, elevated plasma concentration of EPO was maintained up to 7 days. There was no adverse effect during and after the in vivo tests.

Selectively crosslinked hyaluronic acid hydrogels for sustained release formulation of erythropoietin

A novel sustained release formulation of erythropoietin (EPO) was developed using hyaluronic acid (HA) hydrogels. For the preparation of HA hydrogels, adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and analyzed with (1)H NMR. The degree of HA-ADH modification was about 69%. EPO was in situ encapsulated into HA-ADH hydrogels through a selective cross-linking reaction of bis(sulfosuccinimidyl) suberate (BS(3)) to hydrazide group (pK(a) = 3.0) of HA-ADH rather than to amine group (pK(a) > 9) of EPO. The denaturation of EPO during HA-ADH hydrogel synthesis was drastically reduced with decreasing pH from 7.4 to 4.8. The specific reactivity of BS(3) to hydrazide at pH = 4.8 might be due to its low pK(a) compared with that of amine. In vitro release of EPO in phosphate buffered saline at 37 degrees C showed that EPO was released rapidly for 2 days and then slowly up to 4 days from HA-ADH hydrogels. When the hydrogels were dried at 37 degrees C for a day, however, longer release of EPO up to 3 weeks could be demonstrated. According to in vivo release test of EPO from HA-ADH hydrogels in SD rats, elevated EPO concentration higher than 0.1 ng/mL could be maintained from 7 days up to 18 days depending on the preparation methods of HA-ADH hydrogels. There was no adverse effect during and after HA-ADH hydrogel implantation.

Instabilities of proteins: theoretical aspects, degradation products and methods for their detection

Recombinant DNA technology has led to a significant increase in the number of peptide and protein based pharmaceuticals, giving a new approach to combat poorly controlled diseases. This particular development has been reached in the last two decades. However, proteins are highly susceptible of physical and chemical degradation resulting in a decrease or complete loss of biological activities. Reasons for their physical and chemical instabilities and the methods for their examination, become a challenge for the pharmaceutical scientists for successful development of stabile protein - based pharmaceuticals. The stability of protein - based pharmaceuticals is significant in terms of their pharmaceutical quality and biological activity. In addition, a right choice of suitable analytical methods is needed in order to detect an early formation of degradation products or modified forms.

Removal of lipopolysaccharides from protein–lipopolysaccharide complexes by nonflammable solvents

During the recovery of recombinant proteins from gram negative bacteria, many of the methods used to extract proteins from cells release lipopolysaccharides (LPS, endotoxin) along with the protein of interest. In many instances, LPS will co-purify with the target protein due to specific or non-specific protein-LPS interactions. We have investigated the ability of alkanediols to effect the separation of LPS from protein-LPS complexes while the complexes are immobilized on ion exchange chromatographic resins. Proteins were complexed with fluorescently labeled LPS and bound to ion exchange resin. Alkanediol washes of the resins were preformed and the proteins eluted. Column eluates were monitored for LPS and protein by fluorescence and UV spectroscopy, respectively. Alkanediols were effective agents for dissociating LPS from protein-LPS complexes. The efficiency of LPS removal increased with increasing alkanediol chain length. The 1,2-alkanediol isomers were more effective than terminal alkanediol isomers in the separation of LPS from protein-LPS complexes, while the separation of LPS from protein-LPS complexes was more efficient on cation exchangers than on anion exchangers. In addition, it was noted during these investigations that the 1,2-alkanediols increased the retention time of the proteins on the ion exchange resins. Alkanediols provide a safer alternative to the use of other organics such as alcohols or acetonitrile for the separation of LPS from protein due to their lower toxicity and decreased inflammability. In addition, they are less costly than many of the detergents that have been used for similar purposes.