Stem cell-binding peptides for rapid fixation of total hip replacements

SUMMARY ABSTRACTThrough modern surgical advancementstotal hip replacementsTHRhave become one of the most successful implant procedures to dateEven though long term success rates are highthe staggering number of THR procedures performedper year in the United States aloneresults in thousands of failed implants each yearMost implants fail through aseptic loosening and implant instabilityEarlier implant designs utilized various types of synthetic bone cementall of which elicited localized inflammatory responses and stimulated bone resorptionIn responsephysicians shifted towards cementlessporous coated implants and this implant design is now used in a majority of THR proceduresHowevereffective and rapid fixation is critical to both the shortand long term success of hip implantsespecially given the increasingly young and active patient populations opting for THRThusthe need exists for improved hip implant design to facilitate rapid implant fixation in active and mobile patientsUnlike cemented implantscementless implants achieve fixation by press fitting surface modified titanium into bone that eventually allows ingrowthDue to the nature of these implantsadequate bone ingrowth is critical for patient recoveryMaterials such as hydroxyapatite hasten bone ingrowthbut these coatings may promote osteolysis due to wear particles from degradationAs an alternativebone marrow derived mesenchymal stem cellsBMSCsmay be used as a treatment to promote bone formationCurrent methods utilize ex vivo BMSC cultureThis creates several practical and regulatory challengesAs an alternativewe have developed peptides that bind BMSCs with high specificity and affinityOur goal is to attach these peptides onto the surface of the femoral components of hip implants to capture BMSCs from the implant s marrow rich surroundings onto the implant surfaceIn preliminary studieswe have demonstrated that mineralization in stem cell cultures is dependent upon cell concentrationThuswe hypothesize that concentrating BMSCs on titanium implants will speed the patient recovery process and improve short term clinical outcomes for cementless implants