Physiomimetic biocompatibility evaluation of directly printed degradable porous iron implants using various cell types

Additively manufactured (AM) degradable porous metallic biomaterials offer unique opportunities for satisfying the design requirements of an ideal bone substitute. Among the currently available biodegradable metals, iron has the highest elastic modulus, meaning that it would benefit the most from porous design. Given the successful preclinical applications of such biomaterials for the treatment of cardiovascular diseases, the moderate compatibility of AM porous iron with osteoblast-like cells, reported in earlier studies, has been surprising. This may be because, as opposed to static in vitro conditions, the biodegradation products of iron in vivo are transported away and excreted. To better mimic the in situ situations of biodegradable biomaterials after implantation, we compared the biodegradation behavior and cytocompatibility of AM porous iron under static conditions to the conditions with dynamic in situ-like fluid flow perfusion in a bioreactor. Furthermore, the compatibility of these scaffolds with four different cell types was evaluated to better understand the implications of these implants for the complex process of natural wound healing. These included endothelial cells, L929 fibroblasts, RAW264.7 macrophage-like cells, and osteoblastic MG-63 cells. The biodegradation rate of the scaffolds was significantly increased in the perfusion bioreactor as compared to static immersion. Under either condition, the compatibility with L929 cells was the best. Moreover, the compatibility with all the cell types was much enhanced under physiomimetic dynamic flow conditions as compared to static biodegradation. Our study highlights the importance of physiomimetic culture conditions and cell type selection when evaluating the cytocompatibility of degradable biomaterials in vitro. STATEMENT OF SIGNIFICANCE: Additively manufactured (AM) degradable porous metals offer unique opportunities for the treatment of large bony defects. Despite the successful preclinical applications of biodegradable iron in the cardiovascular field, the moderate compatibility of AM porous iron with osteoblast-like cells was reported. To better mimic the in vivo condition, we compared the biodegradation behavior and cytocompatibility of AM porous iron under static condition to dynamic perfusion. Furthermore, the compatibility of these scaffolds with various cell types was evaluated to better simulate the process of natural wound healing. Our study suggests that AM porous iron holds great promise for orthopedic applications, while also highlighting the importance of physio-mimetic culture conditions and cell type selection when evaluating the cytocompatibility of degradable biomaterials in vitro.

[Spinal cord stimulation (SCS) using an 8-pole electrode and double-electrode system as minimally invasive therapy of the post-discotomy and post-fusion syndrome--prospective study results in 34 patients]

AIM

Therapy of a pronounced post-discotomy (PDS) and post-fusion syndrome (PFS) is often unsatisfactory because of the complexity and multifactorial pain genesis. If surgical interventions cannot promise relief and if the entire interdisciplinary spectrum of conservative treatment measures is inadequate, the area of neuromodulative procedures offers spinal cord stimulation (SCS). The objective of this study was to examine the therapeutic possibilities of SCS using an 8-pole electrode and double electrode system in PDS and PFS with extensive back-leg pain areas.

METHOD

An appropriate SCS system was implanted in 34 patients with PDS and PFS. Follow-up examinations were made prospectively over a period of 24 months using general criteria and psychometric test measuring instruments validated for German-language use.

RESULTS

An 8-pole double electrode system was implanted 23 times, a single electrode sufficed in 11 cases. The area of pain was covered in all patients. This required special technical capabilities of the SCS system. The results remained constant over 24 months. The morphine dose could be reduced by at least 50 %. All measuring instruments confirmed a clear reduction in pain and improvement in quality of life as a result of SCS implantation.

CONCLUSION

The SCS is an minimally invasive surgical procedure which can enlarge the therapeutical possibilities of pronounced PDS and PFS resistant to other modes of treatment. Special technical possibilities of parameter setting are required to cover the pain areas.

Expression of the deleted in colorectal cancer gene is related to prognosis in DNA diploid and low proliferative colorectal adenocarcinoma

PURPOSE

Whether or not the deleted in colorectal cancer (DCC) gene is implicated in metastases or in predicting prognosis in patients with colorectal cancer has not previously been substantiated. Our aims were to investigate DCC expression in primary colorectal cancers and in metastases to identify any prognostic significance.

PATIENTS AND METHODS

DCC expression was examined immunohistochemically in 195 primary colorectal adenocarcinomas and in 23 paired primary tumors and lymph node metastases. DNA content and S-phase fraction were measured by flow cytometry.

RESULTS

The absence of DCC expression was observed in 55 primary tumors (28%). DCC negativity was significantly related to poor prognosis in patients with DNA diploid tumors (P =.03) and those with a low S-phase fraction (< 5%, P =.02) but not in patients with nondiploid tumors or those with a higher S-phase fraction. Furthermore, DCC expression retained its prognostic significance in the diploid subgroup after adjusting for sex, age, site, stage, growth pattern, and differentiation (P =.01). DCC expression was similar in primary tumors and their metastases.

CONCLUSION

The absence of DCC predicted a poor outcome in the patients with diploid tumors and those tumors with a low S-phase fraction. Immunohistochemistry may be considered as a practical test to assess prognosis in this subgroup of patients.