The use of tissue sealants to deliver antibiotics to an orthopaedic surgical site with a titanium implant.

BACKGROUND: Orthopaedic surgery is associated with unacceptable infection rates that respond poorly to systemic antibiotics. The objective of this study was to use an animal model for orthopaedic implant infection to examine the ability of a new-generation fibrin tissue sealant to effectively deliver antibiotics to the surgical site. METHODS: The antibiotics cefazolin, fusidic acid or 5-fluorouracil were blended into Vitagel tissue sealant. The release rate of the drugs was measured using HPLC methods and bioactivity was measured by the zone of inhibition method with pathogenic Staphylococcus aureus. The antibiotic activity of the drug-loaded sealant was then tested in rats using infected orthopaedic surgical sites (titanium clip on spine). Efficacy was evaluated by residual bacterial counts on clips, clinical observations of infection, and histological findings. RESULTS: The drugs were released in a controlled manner over 2-4 days. All three antibiotics demonstrated strong antibacterial activity when released from the sealants. None of the treated animals demonstrated systemic illness. Post mortem dissection revealed a well-encapsulated abscess surrounding the titanium clip with erosion of the bony process. Using an inoculum of 1-5 × 10(3) CFU, treatment with antibiotic-loaded fibrin sealant demonstrated reduced infective swelling and reduced bacterial counts on surgical clip swabs compared to control rats or rats treated with antibiotic only. This model allowed for almost 100 % infectivity with a 0 % mortality rate due to infection, mimicking the clinical features of human implant infection. CONCLUSION: The results support the use of antibiotic-loaded commercially available fibrin sealants to prevent infection after implant surgery.

Fucoidan film safely inhibits surgical adhesions in a rat model.

BACKGROUND: The purpose of this study was to evaluate the in vivo efficacy of 13 compounds and to further characterize the load limiting and potential toxicity of the most efficacious compound. The cascade of biochemical and molecular events that results in the formation of postsurgical adhesions provides numerous theoretical opportunities for prophylactic intervention. METHODS: Candidate agents were loaded into sodium hyaluronate (HA) films and administered to male Sprague-Dawley rats using a cecal-sidewall model of surgical adhesions. An adhesion score was obtained for each rat based on the strength and extent of the adhesions. The most efficacious agent, fucoidan, was further evaluated in a load-limiting study with a concentration range of 0.0033 to 33% w/w per film. The potential toxicity of fucoidan was evaluated in a separate study by comparison of hematology findings, blood chemistry, urinalysis, and incision thickness from rats administered control films or 33% w/w fucoidan films 1 to 4 d prior to sacrifice. RESULTS: Fucoidan loaded films reduced adhesion scores by approximately 90% compared with control films (P<0.05). A total of 50% to 100% of animals were adhesion free at fucoidan film loadings of 0.33% to 33% w/w compared with all control film animals having adhesions. No adverse effects were observed from 33% w/w fucoidan films equivalent to approximately 30 mg fucoidan/kg body weight. CONCLUSIONS: Local administration of fucoidan film during rat cecal-sidewall surgery safely reduced adhesion scores by approximately 90% and resulted in 50% to 100% of animals being adhesion free.

Engraftment of NOD/SCID-beta2 microglobulin null mice with multilineage neoplastic cells from patients with myelodysplastic syndrome.

The development of immunodeficient mouse xenograft models has greatly facilitated the investigation of some human hematopoietic malignancies, but application of this approach to the myelodysplastic syndromes (MDSs) has proven difficult. We now show that cells from most MDS patients (including all subtypes) repopulate nonobese diabetic-severe combined immunodeficient (scid)/scid-beta2 microglobulin null (NOD/SCID-beta2m(-/-)) mice at least transiently and produce abnormal differentiation patterns in this model. Normal marrow transplants initially produce predominantly erythroid cells and later predominantly B-lymphoid cells in these mice, whereas most MDS samples produced predominantly granulopoietic cells. In 4 of 4 MDS cases, the regenerated cells showed the same clonal markers (trisomy 8, n = 3; and 5q-, n = 1) as the original sample and, in one instance, regenerated trisomy 8(+) B-lymphoid as well as myeloid cells were identified. Interestingly, the enhanced growth of normal marrow obtained in NOD/SCID-beta2m(-/-) mice engineered to produce human interleukin-3, granulocyte-macrophage colony-stimulating factor, and Steel factor was seen only with 1 of 7 MDS samples. These findings support the concept that human MDS originates in a transplantable multilineage hematopoietic stem cell whose genetic alteration may affect patterns of differentiation and responsiveness to hematopoietic growth factors. They also demonstrate the potential of this new murine xenotransplant model for future investigations of MDS.

Stromal-derived factor 1 inhibits the cycling of very primitive human hematopoietic cells in vitro and in NOD/SCID mice.

Stromal-derived factor 1 (SDF-1) is a -CXC- chemokine that plays a critical role in embryonic and adult hematopoiesis, and its specific receptor, CXCR4, has been implicated in stem cell homing. In this study, it is shown that the addition of SDF-1 to long-term cultures (LTCs) of normal human marrow can selectively, reversibly, and specifically block the S-phase entry of primitive quiescent erythroid and granulopoietic colony-forming cells (CFCs) present in the adherent layer. Conversely, addition of anti-SDF-1 antibody or SDF-1(G2), a specific CXCR4 antagonist, to preactivated human LTCs prevented both types of primitive CFCs from re-entering a quiescent state, demonstrating that endogenous SDF-1 contributes to the control of primitive CFC proliferation in the LTC system. Interestingly, SDF-1 failed to arrest the proliferation of primitive chronic myeloid leukemia CFCs in the adherent layer of LTCs containing normal marrow stromal cells. In vivo, injection of SDF-1 arrested the cycling of normal human LTC-initiating cells as well as primitive CFCs in the marrow of nonobese diabetic/severe combined immunodeficient mice engrafted with human cord blood cells. Conversely, injection of the antagonist, SDF-1(G2), reactivated the cycling of quiescent primitive human CFCs present in the marrow of mice engrafted with human marrow cells. These studies are the first to demonstrate a potential physiological role of SDF-1 in regulating the cell-cycle status of primitive hematopoietic cells and suggest that the deregulated cycling activity of primitive chronic myeloid leukemia (CML) cells is due to the BCR-ABL-mediated disruption of a pathway shared by multiple chemokine receptors.