Missing osteoconductive effect of a resorbable PEO/PBT copolymer in human bone defects: A clinically relevant pilot study with contrary results to previous animal studies

Abstract

PEO/PBT 70/30 (POLYACTIVE(R) 70/30), a degradable porous copolymer with elastic properties, was found to be osteoconductive in many animal studies. The aim of this study was to determine the osteoconductive effect in a human paired control iliac defect model. In seven patients undergoing anterior spinal interbody fusion surgery, two bicortical iliac defects for autograft harvesting were created. The defect size was identical for both defects measuring about 40 x 15 mm (group I). One defect was filled with the degradable implants, whereas the remaining one was left untreated as a control. The defect site for treatment was chosen randomly. In three further patients, only one defect measuring about 40 x 35 mm was created (group II). All patients were examined clinically and radiologically by spiral-CT after 1, 6, 12, 24, and 52 weeks. Three-dimensional reconstructions as well as CT-volumetric measurements using 1 mm sections were used as evaluation methods. In group I, a two-tailed paired t-test showed that the treated defects had significantly less formation of new bone than the untreated ones (p < 0.05 after 12 weeks, p < 0.01 after 52 weeks). Also, in group II, not much bone ingrowth could be observed. The histological evaluation of one patient in group I revealed no bone within the pores, and a fibrous layer between bone and implant was always present. Therefore, PEO/PBT 70/30 cannot be recommended as a bone substitute for clinical use. Differences in bone regeneration between humans and certain animal species as well as inapplicable defect models in previous animal studies are discussed as possible reasons for the failure.

Biodegradable PEG-Based Amphiphilic Block Copolymers for Tissue Engineering Applications

“…128 In a human trail, PEGT-PBT (70% PEG) foam blocks were implanted into iliac crest defects and the bone healing was compared to untreated control defects. 129 Nine months after implantation, the PEGT-PBT foams resulted in limited inflammation but were encapsulated by fibrous tissue. The PEGT-PBT foams failed to calcify even after one year, and the un-treated control defects resulted in greater bone formation than the PEGT-PBT filled defects.…”

Prognostic significance of serum thymidine phosphorylase concentration in esophageal squamous cell carcinoma

“…Several subcutaneous and intra‐bone (tibia) implantations of dense blocks and porous films in rats showed bone bonding, calcification, and degradation for PEOT/PBT copolymers with high PEO content (60 and 70 weight percent PEO containing soft segment) 5–8. However, these effects were not seen after implantation of porous blocks in goat9 and human10 ilea. We intend to prepare porous PEOT/PBT scaffolds on which a patient's own bone marrow cells can be cultured.…”

Toward Engineering a Novel Transplantation Site for Human Pancreatic Islets

“…In animal studies, Polyactive was shown to be surrounded by capillary-rich granulation suggesting that the polymer itself contributes to vascularization (43). Although Polyactive triggered the influx of immune cells at the implantation site in animal studies (43), application of the copolymer in the clinic was not associated with any side effects, and no inflammatory or abnormal cellular response was found 1 year after implantation (44). …”