No abstract

Slow and incomplete osseointegration and loss of osseointegration are major problems in dental and bone implants. We designed implants with interconnected 3D‐tubulous structures and hypothesized that such interconnecting 3D (I3D) structures would serve as a repository for chemoattractants to recruit stem cells to promote osseointegration. A concept Laser Mlab‐cusing‐R laser‐powder‐bed‐fusion (LPBF) 3D printing system was used to produce titanium implants with designed features. The implants were loaded (coated) with stromal cell–derived factor‐1 alpha (SDF‐1α), and subjected to stem cell recruitment. Implants were then surgically transplanted into the rabbit skull bone. After 12 weeks, osseointegration was analyzed by reverse‐torque test and the implants were examined for calcium deposition by Alizarin Red staining. The I3D implants attracted significantly more stem cells than solid implants when coated (loaded) with SDF‐1α. Greater torque force was needed to extract the I3D implants with 200 and 300 µm I3D structures than to extract solid implants from the skull. Generally, more calcium deposition was observed on the I3D implants than on the solid counterparts. LPBF 3D printing can be used to fabricate implants with complex structures. I3D‐tubulous structures of implants can retain chemoattractant for recruitment of stem cells to enhance osseointegration.

No abstract

Both endovascular repair (EVR) and open repair (OR) surgery of thoraco-abdominal aortic aneurysms cause spinal cord (SC) injury that can lead to paraparesis or paraplegia. It has been assumed that mechanisms responsible for SC damage after EVR are similar to those after OR. This pilot study compared the pathophysiology of SC injury after EVR versus OR using a newly developed EVR dog model. An increasing number of stents similar to those used in patients were inserted in the aorta of three dogs to ensure thoracic or thoracic plus lumbar coverage. The aorta of OR dogs was cross-clamped for 45 min. Behavior assessment demonstrated unique patterns of proprioceptive ataxia and evolving paraparesis in EVR versus irreversible paraplegia in OR. MRI showed posterior signal in lumbar SC after EVR versus central cord edema after OR. Histopathology showed white matter edema in L3–L5 localized to the dorsal column medial lemniscus area associated with loss of myelin basic protein but not neurons after EVR, versus massive neuronal loss in the gray matter in L3–L5 after OR. Metabolome analysis demonstrates a distinctive chemical fingerprint of cellular processes in both interventions. Our results call for the development of new therapeutics tailored to these distinct pathophysiologic findings.