Intra-aneurysmal embolization of cellulose porous beads to regenerate vessel wall: an experimental study.

PURPOSE: Although the treatment of intracranial cerebral aneurysms with detachable coils is now widely accepted, the problem of coil compaction and recanalization remains unsolved. If the vessel wall can be regenerated at the neck orifice of an aneurysm, thereby reducing the blood flow into the aneurysm, the recurrence rate of the aneurysm would decrease. Accordingly, we aimed to insert cellulose porous beads (CPBs) into rat models of external carotid artery (ECA) aneurysm and study their efficacy in promoting vessel wall regeneration. METHODS: Using a rat aneurysm model, we examined the tissue response to CPBs that were inserted into the ligated ECA sac of rats. The sacs were removed on days 14, 42, 84, and 180 after insertion and subjected to conventional and immunohistochemical examination. We evaluated the tissue response in the ECA sacs and observed the vessel wall regeneration progress. RESULTS: At the neck orifice of the aneurysm in which the CPB was inserted, a layer of regenerating α-smooth muscle actin-positive spindle cells was observed on day 14. The regenerative cell layer gradually thickened until day 42 and, thereafter, the thickness remained unchanged until day 180. A monolayer of factor VIII-positive cells also appeared at the neck orifice on day 14 and covered the entire orifice until day 180. The CPBs were stably localized in the sac without degradation or signs of inflammation. CONCLUSION: CPBs may be promising as embolic materials that can induce stable vessel wall regeneration at the neck orifice of an aneurysm without surrounding inflammatory reactions.

Intravascular tissue reactions induced by various types of bioabsorbable polymeric materials: correlation between the degradation profiles and corresponding tissue reactions.

INTRODUCTION: Several different bioabsorbable polymeric coil materials are currently used with the goal of improving treatment outcomes of endovascular embolization of intracranial aneurysms. However, little is known about the correlation between polymer degradation profiles and concomitant tissue responses in a blood vessel. The authors describe in vitro degradation characteristics of nine different polymeric materials and their corresponding tissue responses induced in rabbit carotid arteries. METHODS: Mass loss and molecular weight loss of nine commercially available bioabsorbable sutures were evaluated in vitro up to16 weeks. The same nine materials, as well as platinum coils, were implanted into blind-end carotid arteries (n = 44) in rabbits, and their tissue reactions were evaluated histologically 14 days after the implantation. RESULTS: Five of the nine polymers elicited moderate to strong tissue reactions relative to the remaining materials. While polymer mass loss did not correlate with their histologic findings, polymers that showed a faster rate of molecular weight loss had a tendency to present more active tissue reactions such as strong fibrocellular response around the implanted material with a moderate inflammatory cell infiltration. Maxon exhibited the fastest rate of molecular weight loss and poly-l-lactic acid the slowest. CONCLUSIONS: The rate of molecular weight loss may be an important factor that is associated with the degree of bioactivity when bioabsorbable polymers are implanted into blood vessels. For further quantitative analysis, additional experiments utilizing established aneurysm models need to be conducted.

Retro-odontoid pseudotumor without atlantoaxial subluxation.

A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial subluxation (AAS). Here, we report a patient with ROP but without AAS. The patient was a 72-year-old man who did not have a history of rheumatoid arthritis or trauma to the head and neck. The patient was admitted to our hospital with gait disturbance, progressive motor weakness in both upper extremities and sensory disturbance in all four extremities. MRI showed a retro-odontoid mass with severe compression of the cervical spinal cord. A CT scan showed spondylotic changes in C5, C6, and C7 and bilateral facet fusion between C3 and C4. Dynamic radiography showed no evidence of AAS; there was loss of mobility at C2-C7 and excessive mobility at C1. Intraoperative pathological examination revealed that the lesion was a pseudotumor; therefore, posterior C1-C2 fixation was performed. MRI performed 6 months after the operation revealed that the pseudotumor was markedly reduced. To the best of our knowledge, patients with ROP without AAS are uncommon.

Coils coated with the cyclic peptide SEK-1005 accelerate intra-aneurysmal organization.

BACKGROUND: Although the treatment of intracranial aneurysms with detachable coils is now widely accepted, the problem of coil compaction and recanalization remains to be solved. OBJECTIVE: To prevent recanalization by inducing intra-aneurysmal organization through prepared platinum coils coated with a novel cyclic peptide, SEK-1005, which can accelerate wound healing. METHODS: Using a rat aneurysm model, we examined the tissue response to these coils. An SEK-1005-coated coil (SC) or unmodified coil was inserted into the ligated external carotid artery (ECA) sac of rats. The sacs were removed on day 14 or 42 after coil insertion and subjected to conventional and immunohistochemical examination. We evaluated the tissue response in the ECA sacs and compared the percentage of organized areas in the ECA sacs of rats with SCs and unmodified coils. RESULTS: In SC rats, tissue organization was accelerated and the proliferation of α-smooth muscle actin- and vimentin-positive cells was promoted. On days 14 and 42, tissue organization was significantly greater in the ECA sacs of rats with SCs. CONCLUSION: SCs accelerated intra-aneurysmal organization in our rat aneurysm model suggesting that platinum coils coated with the novel cyclic peptide SEK-1005 may prevent recanalization and improve the clinical outcome in patients treated by coil embolization.