Intraoperative engineering of osteogenic grafts combining freshly harvested, human adipose-derived cells and physiological doses of bone morphogenetic protein-2

Engineered osteogenic constructs for bone repair typically involve complex and costly processes for cell expansion. Adipose tissue includes mesenchymal precursors in large amounts, in principle allowing for an intraoperative production of osteogenic grafts and their immediate implantation. However, stromal vascular fraction (SVF) cells from adipose tissue were reported to require a molecular trigger to differentiate into functional osteoblasts. The present study tested whether physiological doses of recombinant human BMP-2 (rhBMP-2) could induce freshly harvested human SVF cells to generate ectopic bone tissue. Enzymatically dissociated SVF cells from 7 healthy donors (1 x 10(6) or 4 x 10(6)) were immediately embedded in a fibrin gel with or without 250 ng rhBMP-2, mixed with porous silicated calcium-phosphate granules (Actifuse(®), Apatech) (final construct size: 0.1 cm(3)) and implanted ectopically for eight weeks in nude mice. In the presence of rhBMP-2, SVF cells not only supported but directly contributed to the formation of bone ossicles, which were not observed in control cell-free, rhBMP-2 loaded implants. In vitro analysis indicated that rhBMP-2 did not involve an increase in the percentage of SVF cells recruited to the osteogenic lineage, but rather induced a stimulation of the osteoblastic differentiation of the committed progenitors. These findings confirm the feasibility of generating fully osteogenic grafts using an easily accessible autologous cell source and low amounts of rhBMP-2, in a timing compatible with an intraoperative schedule. The study warrants further investigation at an orthotopic site of implantation, where the delivery of rhBMP-2 could be bypassed thanks to the properties of the local milieu.

The leukemogenic AF4-MLL fusion protein causes P-TEFb kinase activation and altered epigenetic signatures

Expression of the AF4-MLL fusion protein in murine hematopoietic progenitor/stem cells results in the development of proB acute lymphoblastic leukemia. In this study, we affinity purified the AF4-MLL and AF4 protein complexes to elucidate their function. We observed that the AF4 complex consists of 11 binding partners and exhibits positive transcription elongation factor b (P-TEFb)-mediated activation of promoter-arrested RNA polymerase (pol) II in conjunction with several chromatin-modifying activities. In contrast, the AF4-MLL complex consists of at least 16 constituents including P-TEFb kinase, H3K4(me3) and H3K79(me3) histone methyltransferases (HMT), a protein arginine N-methyltransferase and a histone acetyltransferase. These findings suggest that the AF4-MLL protein disturbs the fine-tuned activation cycle of promoter-arrested RNA Pol II and causes altered histone methylation signatures. Thus, we propose that these two processes are key to trigger cellular reprogramming that leads to the onset of acute leukemia.

Adipose tissue-derived progenitors for engineering osteogenic and vasculogenic grafts

The current need for bone grafts in orthopedic and reconstructive surgery cannot be satisfied by autologous tissue transplant due to its limited availability and significant associated morbidity. Tissue engineering approaches could supply sufficient amounts of bone substitutes by exploiting the ability to harvest autologous osteogenic progenitors associated with suitable porous materials. However, the generation of clinically relevant-sized constructs is critically hampered by limited vascularization, with consequent engraftment and survival only of a thin outer shell, upon in vivo implantation. To overcome this limitation, different non-mutually exclusive approaches have recently been developed to promote or accelerate graft vascularization, from angiogenic growth factor gene delivery to surgical pre-vascularization of the construct before implantation. A simple, promising strategy involves the co-culture of vasculogenic cells to form an intrinsic vascular network inside the graft in vitro, which can rapidly anastomose with the host blood vessels in vivo. Recent data have shown that adipose tissue-derived stromal vascular fraction (SVF) may provide an efficient, convenient, and autologous source for both osteogenic and endothelial cells. When SVF progenitors were cultured in appropriate bioreactor systems and ectopically implanted, a functional vascular network connected to the host was formed concomitantly to bone formation. Future studies should aim at demonstrating that this approach effectively supports survival of scaled up cell-based bone grafts at an orthotopic site. The procedure should also be adapted to become compatible with an intra-operative timeline and complemented with the definition of suitable potency markers, to facilitate its development into a simplified, reproducible, and cost-effective clinical treatment.

[Appendicitis in childhood: correlation of clinical data with histopathological findings]

BACKGROUND

Quantifying the histopathological diagnoses of appendectomies in daily routine paidopathology results in a high percentage of appendices without histomorphological sign of acute inflammation. To identify clinical factors significantly associated with the morphological diagnosis, histopathological findings and clinical data--documented in patients' files--were examined.

PATIENTS

All 856 children (age: 5 m-15 yrs) whose appendix had been resected within a 7-year-period were--depending on the histopathological diagnoses--allocated to the group "appendix without" resp. "appendix with signs of acute inflammation".

METHOD

All files were examined concerning anamnestic data, clinical signs of acute appendicitis and laboratory parameters. The data were analysed by χ(2)-test and Wilcoxon-test concerning differences between the 2 groups with regard to the anamnestic and clinical facts and parameters. Using binary logistic regression, these clinical parameters were analyzed in correlation with the histopathological diagnoses.

RESULTS

By consideration of the factors "leucocyte count", "vomiting" and "percussion tenderness" 75% of the children would have been allocated to the accurate postoperative pathomorphological diagnosis.

CONCLUSIONS

There was a significant correlation of "leucocyte count", "vomiting" and "percussion tenderness" with histopathology in 75% of the children. As hence 25% were not allocated correctly this combination is no unequivocal combination for prediction or exclusion of an acute appendicitis. Hence, even with these statistically significant parameters a comparably high percentage of falsely-positive appendectomies has to be anticipated.

[Analysis of an ophthalmic pathology cohort of human fetal eyes with regard to interesting findings]

OBJECTIVE

Information on the evaluation of prenatal ocular findings is sparse. This article provides an overview of the morphology in a cohort of human fetal eyes, with particular emphasis on interesting findings.

METHODS

The study investigated 216 eyes from 115 human fetuses.

RESULTS

The majority of fetal eyes presented with a regular phenotype. Rarely, unexpected findings were discovered in fetuses with or without systemic malformations.

CONCLUSION

Routine evaluation of fetal eyes reveals-albeit rarely-new aspects providing further knowledge and occasionally enabling the exact classification of syndromes.

Renal cell carcinoma with Xp11.2 translocation in a 7-year-old boy

BACKGROUND

More than 90% of pediatric renal tumors are nephroblastomas while renal cell carcinomas (RCC) are rare in children (< 5%).

PATIENT

According to the clinical diagnoses of a nephroblastoma stage IV a 7-year-old boy with a kidney tumor and peripheral pulmonary lesion was preoperatively treated for 8 weeks with Vincristine, Actinomycin D and Adriamycin. The resected kidney displayed a RCC with Xp11.2 translocation. There was no tumor regression and the pulmonary lesion was no longer detectable. Hence chemotherapy was put to a halt.

CONCLUSION

Fine needle aspiration biopsy (FNA) would have allowed to adjust the tumor subtype. Prognosis of pediatric RCC with translocation seems more favourable than without translocation though definitive evidence will only be possible by documentation in a clinical diagnose-related register.

Towards an intraoperative engineering of osteogenic and vasculogenic grafts from the stromal vascular fraction of human adipose tissue

Grafts generated by cultivation of progenitor cells from the stromal vascular fraction of human adipose tissue have been proven to have osteogenic and vasculogenic properties in vivo. However, in vitro manufacture of such implants is challenged by complex, impractical and expensive processes, and requires implantation in a separate surgery. This study investigates the feasibility of an intraoperative approach to engineer cell-based bone grafts with tissue harvest, cell isolation, cell seeding onto a scaffold and subsequent implantation within a few hours. Freshly isolated adipose tissue cells from a total of 11 donors, containing variable fractions of mesenchymal and endothelial progenitors, were embedded at different densities in a fibrin hydrogel, which was wrapped around bone substitute materials based on beta-tricalcium phosphate (ChronOS), hydroxyapatite (Engipore), or acellular xenograft (Bio-Oss). The resulting constructs, generated within 3 hours from biopsy harvest, were immediately implanted ectopically in nude mice and analysed after eight weeks. All explants contained blood vessels formed by human endothelial cells, functionally connected to the recipient's vasculature. Human origin cells were also found within osteoid structures, positively immunostained for bone sialoprotein and osteocalcin. However, even with the highest loaded cell densities, no frank bone tissue was detected, independently of the material used. These results provide a proof-of-principle that an intraoperative engineering of autologous cell-based vasculogenic bone substitutes is feasible, but highlight that - in the absence of in vitro commitment--additional cues (e.g., low dose of osteogenic factors or orthotopic environmental conditions) are likely needed to support complete osteoblastic cell differentiation and bone tissue generation.

Platelet lysate as a serum substitute for 2D static and 3D perfusion culture of stromal vascular fraction cells from human adipose tissue

Fetal bovine serum (FBS) and fibroblast growth factor (FGF)-2 are key supplements for the culture of stromal vascular fraction (SVF) cells from adipose tissue, both for typical monolayer (2D) expansion and for streamlined generation of osteogenic-vasculogenic grafts in 3D perfusion culture. The present study investigates whether factors present in human platelet lysate (PL) could substitute for FBS and FGF-2 in 2D and 3D culture models of SVF cells from human lipoaspirates. SVF cells were grown in medium supplemented with 10% FBS+FGF-2 or with 5% PL. In 2D cultures, PL initially supported SVF cell proliferation, but resulted in growth arrest shortly after the first passage. Freshly isolated SVF cells cultured with both media under perfusion for 5 days within 3D ceramic scaffolds induced bone formation after subcutaneous implantation in nude mice. However, blood vessels of donor origin were generated only using FBS+FGF-2-cultured cells. This was unexpected, because the proportion of CD34+/CD31+ endothelial lineage cells was significantly higher with PL than that of FBS+FGF-2 (33% vs. 3%, respectively). These results support the use of PL as a substitute of FBS+FGF-2 for short-term culture of human SVF cells, and indicate that more specific serum-free formulations are required to maintain a functionally vasculogenic fraction of SVF cells expanded under 3D perfusion.

Genetic variants in the USF1 gene are associated with low-density lipoprotein cholesterol levels and incident type 2 diabetes mellitus in women: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002

OBJECTIVE

Upstream transcription factor 1 (USF1) regulates genes of glucose and lipid metabolism. Polymorphisms in the USF1 gene showed association with familial combined hyperlipidemia and lipid parameters. The aim of our study was to examine the associations between USF1 polymorphisms and lipid parameters as well as incident type 2 diabetes mellitus (T2DM) in German Caucasians.

DESIGN

We genotyped eight polymorphisms in the USF1 gene in 2067 middle-aged (35-74 years) individuals including 498 incident T2DM cases and 1569 non-cases of the population-based case-cohort study from the MONICA/KORA Augsburg project.

METHODS

Six polymorphisms and their haplotypes were analyzed using multivariable linear regression and Cox proportional hazards models.

RESULTS

Polymorphism rs3737787 was inversely associated with incident T2DM in women with decreased risk for female heterozygotes compared with women homozygous for the major allele (Hazard ratio=0.57; 95% confidence intervals: 0.38-0.87; P=0.008). After correction for multiple testing, significance remained. Polymorphisms rs3813609 and rs1556259 were significantly associated with reduction in low-density lipoprotein (LDL) cholesterol (p(NOM)=0.001; p(NOM)=0.00002) in women. Analyses also indicated associations of haplotypes with LDL cholesterol in women, but the association lost statistical significance after correction for multiple testing. Total serum cholesterol (TC) and high-density lipoprotein (HDL) cholesterol were weakly associated (P<0.05) with USF1 polymorphisms in women. No significant associations were found in men.

CONCLUSIONS

In this large population-based study, statistically significant associations of USF1 polymorphisms with incident T2DM and LDL cholesterol were found in women, but not in men. Genetic variants in the USF1 gene showed weak or no associations with TC and HDL cholesterol.

[Investigation of neural stem cell-derived donor contribution in the inner ear following blastocyst injection]

BACKGROUND

Utilising the enormous proliferation and multi-lineage differentiation potentials of somatic stem cells represents a possible therapeutical strategy for diseases of non-regenerative tissues like the inner ear. In the current study, the possibility of murine neural stem cells to contribute to the developing inner ear following blastocyst injection was investigated.

METHODS

Fetal brain-derived neural stem cells from the embryonic day 14 cortex of male mice were isolated and expanded for four weeks in neurobasal media supplemented with bFGF and EGF. Neural stem cells of male animals were harvested, injected into blastocysts and the blastocysts were transferred into pseudo-pregnant foster animals. Each blastocyst was injected with 5-15 microspheres growing from single cell suspension from neurospheres dissociated the day before. The resulting mice were investigated six months POST PARTUM for the presence of donor cells. Brainstem evoked response audiometry (BERA) was performed in six animals. To visualize donor cells Lac-Z staining was performed on sliced cochleas of two animals. In addition, the cochleas of four female animals were isolated and genomic DNA of the entire cochlea was analyzed for donor contribution by Y-chromosome-specific PCR.

RESULTS

All animals had normal thresholds in brainstem evoked response audiometry. The male-specific PCR product indicating the presence of male donor cells were detected in the cochleas of three of the four female animals investigated. In two animals, male donor cells were detected unilateral, in one animal bilateral.

CONCLUSION

The results suggest that descendants of neural stem cells are detectable in the inner ear after injection into blastocysts and possess the ability to integrate into the developing inner ear without obvious loss in hearing function.

Genetic deletion of JNK1 and JNK2 aggravates the DSS-induced colitis in mice

The c-Jun N-terminal kinases (JNKs) are considered as novel targets for therapy of inflammatory bowel diseases (IBD). However, the relevant JNK isoforms have to be elucidated. Here, we analyze the individual contribution of the JNK1 and JNK2 isoforms in a dextran sulfate sodium (DSS) model of experimental colitis. JNK1 and JNK2 knockout mice (JNK1 ko, JNK2 ko) and their wild-type controls (WT1, WT2) received three cycles of DSS treatment, each consisting of 1.7% DSS for 5 days, followed by 5 days with water. Animals were daily evaluated by a disease activity index (DAI) comprising measurement of body weight, estimation of stool consistency, and test for occult blood/gross rectal bleeding. After 30 days all animals were sacrificed, and the inflamed intestine was histologically evaluated by a crypt damage score. Unexpectedly, neither JNK1 ko nor JNK2 ko prevented mice from developing a chronic colitis when compared to wild-type controls WT1 and WT2, respectively. On the contrary, DAI and mortality were aggravated in JNK2 ko compared to WT2. DAI and mortality did not differ between JNK1 ko and WT1, but the histological crypt damage score was significantly enhanced in the cecum of JNK1 ko mice. Genetic deletion of JNK2 worsens the disease outcome in an experimental model of murine colitis. We hypothesize that the functional deletion of the otherwise proapoptotic JNK2 prolongs the activity of proinflammatory immune cells with deterioration of disease activity.

[Diverticulum of the ductus arteriosus. Cause of traumatic aortic ruptures?]

INTRODUCTION

According to angiographic studies 9-26% of all adult aortae show a ductus arteriosus diverticulum (DAD), i.e. an indention of the aortic wall at the insertion of the obliterated ductus arteriosus. This region is predisposed for traumatic aortic rupture. Up to now fixation at the transition from aorta transversa to fixed aorta descendens is regarded as cause. It is unclear whether ductus diverticulum favours traumatic aortic rupture.

MATERIAL AND METHODS

A total of 143 thoracic aortas (female symbol:37; male symbol:106, 17-91 years) were scanned histomorphologically for DAD. Calcification was quantified by CT multislice volume scan.

RESULTS

A DAD was detected in 44% of macroscopically non-calcified and slightly calcified aortic specimens. Histologically, autochthonal elastic and collagenous fibres of the media were disrupted. CT in macroscopically non-calcified aortas proved isolated calcification in 78%.

DISCUSSION

The incidence of 44% DAD-higher than in angiographic studies-can be explained by the method (histopathology), allowing diagnosis of diverticula down to microm. These morphological alterations are to be seen, at least in part, as a causative factor for the predilection to traumatic aortic ruptures.

Pulmonale segmentale mediolytische Arteriopathie

Segmental mediolytic arteriopathy (SMA) is defined as non-inflammatory arteriopathy with mediolysis due to segmental loss of media and consecutive formation of vascular gaps. Up to now, less than 40 cases of visceral and cerebral SMA and, to our knowledge, only one case of pulmonary SMA have been reported. We present the history of a 21 year old female patient, admitted to hospital with hemoptysis, but without other symptoms. Apart from two lesions in the sixth and tenth pulmonary segment, documented by CT and interpreted as colliquations, there were no other clinical and laboratory findings. Repeated bronchoscopy supplied no further information. Histomorphology of the resected lesion revealed SMA without evidence of vasculitis. Wegener's disease could be excluded. The aetiology of the disease is still unknown. Acute vasospasm (due to inappropriate reactions to catecholamine or endothelial dysfunction), as well as SMA as a precursor or subtype of fibromuscular dysplasia, are two theories still under discussion.