Systematic review on the application of 3D-bioprinting technology in orthoregeneration: current achievements and open challenges

BACKGROUND

Joint degeneration and large or complex bone defects are a significant source of morbidity and diminished quality of life worldwide. There is an unmet need for a functional implant with near-native biomechanical properties. The potential for their generation using 3D bioprinting (3DBP)-based tissue engineering methods was assessed. We systematically reviewed the current state of 3DBP in orthoregeneration.

METHODS

This review was performed using PubMed and Web of Science. Primary research articles reporting 3DBP of cartilage, bone, vasculature, and their osteochondral and vascular bone composites were considered. Full text English articles were analyzed.

RESULTS

Over 1300 studies were retrieved, after removing duplicates, 1046 studies remained. After inclusion and exclusion criteria were applied, 114 articles were analyzed fully. Bioink material types and combinations were tallied. Cell types and testing methods were also analyzed. Nearly all papers determined the effect of 3DBP on cell survival. Bioink material physical characterization using gelation and rheology, and construct biomechanics were performed. In vitro testing methods assessed biochemistry, markers of extracellular matrix production and/or cell differentiation into respective lineages. In vivo proof-of-concept studies included full-thickness bone and joint defects as well as subcutaneous implantation in rodents followed by histological and µCT analyses to demonstrate implant growth and integration into surrounding native tissues.

CONCLUSIONS

Despite its relative infancy, 3DBP is making an impact in joint and bone engineering. Several groups have demonstrated preclinical efficacy of mechanically robust constructs which integrate into articular joint defects in small animals. However, notable obstacles remain. Notably, researchers encountered pitfalls in scaling up constructs and establishing implant function and viability in long term animal models. Further, to translate from the laboratory to the clinic, standardized quality control metrics such as construct stiffness and graft integration metrics should be established with investigator consensus. While there is much work to be done, 3DBP implants have great potential to treat degenerative joint diseases and provide benefit to patients globally.

Myo/Nog cell regulation of bone morphogenetic protein signaling in the blastocyst is essential for normal morphogenesis and striated muscle lineage specification

Cells that express MyoD mRNA, the G8 antigen and the bone morphogenetic protein (BMP) inhibitor noggin (Nog) are present in the epiblast before gastrulation. Ablation of "Myo/Nog" cells in the blastocyst results in an expansion of canonical BMP signaling and prevents the expression of noggin and follistatin before and after the onset of gastrulation. Once eliminated in the epiblast, they are neither replaced nor compensated for as development progresses. Older embryos lacking Myo/Nog cells exhibit severe axial malformations. Although Wnts and Sonic hedgehog are expressed in ablated embryos, skeletal muscle progenitors expressing Pax3 are missing in the somites. Pax3+ cells do emerge adjacent to Wnt3a+ cells in vitro; however, few undergo skeletal myogenesis. Ablation of Myo/Nog cells also results in ectopically placed cardiac progenitors and cardiomyocytes in the somites. Reintroduction of Myo/Nog cells into the epiblast of ablated embryos restores normal patterns of BMP signaling, morphogenesis and skeletal myogenesis, and inhibits the expression of cardiac markers in the somites. This study demonstrates that Myo/Nog cells are essential regulators of BMP signaling in the early epiblast and are indispensable for normal morphogenesis and striated muscle lineage specification.

[High blood pressure and alcohol consumption]

The possible effects of individual alcoholic beverages on blood pressure continue to arouse interest. There is a positive relationship between alcohol intake and blood pressure. The nature of this relationship still remains unresolved. Authors led studies where different patterns of drinking were assessed. First, different mechanisms are involved for generating hypertension when alcohol drinking. Vasoconstriction effects and modification of smooth muscles are well established factors of alcohol-induced hypertension. Calcium movements are also involved. Men and women are affected by hypertensive effects of excessive alcohol consumption. Drinking alcohol during meals is a probable protective factor of developing hypertension. Reducing alcohol consumption provokes a significant diminution of hypertension.

[The use of psychotropic drugs in alcoholism]

Comorbid psychiatric disorders occur frequently in patients with alcohol dependence. Psychotropic medications as antidepressants, benzodiazepines, antipsychotic or hypnotic medications are sometimes useful with alcoholic patients. Their prescription has to be cautious, well-assessed and time-framed. Globally, antidepressants have very little effect on alcohol outcomes meanwhile benzodiazepines are the drug of choice for alcohol withdrawal. But their use has to be very careful because of their addictive potential. Antipsychotic medications have no real indications. Considering the risk of relapse related to insomnia, sedative medications might be useful after detoxification to prevent relapse.

The use of the aquatic moss Fontinalis antipyretica L. ex Hedw. as a bioindicator for heavy metals: 3. Cd2+ accumulation capacities and biochemical stress response of two Fontinalis species

We studied heavy metal stress responses of two Fontinalis species, F. antipyretica and F. dalecarlica, collected from two habitats in Germany and Canada. The capacities of the two species for extracellular adsorption (biosorption) and intracellular uptake (bioaccumulation) of Cadmium (Cd2+) were investigated in the laboratory. Time-dependent Cd2+ adsorption by cell wall and intracellular uptake differed significantly between the two species. These differences were related to the number of Cd2+ binding sites, resulting from differences in leaflet surface and cell wall composition. Glutathione (GSH) levels in response to Cd2+ exposure were monitored over a 10-day period. GSH synthesis differed significantly between the two species. Both Fontinalis species appear to be suitable for heavy metal biomonitoring in aquatic habitats.

The use of the aquatic moss Fontinalis antipyretica L. ex Hedw. as a bioindicator for heavy metals: 3. Cd2+ accumulation capacities and biochemical stress response of two Fontinalis species

We studied heavy metal stress responses of two Fontinalis species, F. antipyretica and F. dalecarlica, collected from two habitats in Germany and Canada. The capacities of the two species for extracellular adsorption (biosorption) and intracellular uptake (bioaccumulation) of Cadmium (Cd2+) were investigated in the laboratory. Time-dependent Cd2+ adsorption by cell wall and intracellular uptake differed significantly between the two species. These differences were related to the number of Cd2+ binding sites, resulting from differences in leaflet surface and cell wall composition. Glutathione (GSH) levels in response to Cd2+ exposure were monitored over a 10-day period. GSH synthesis differed significantly between the two species. Both Fontinalis species appear to be suitable for heavy metal biomonitoring in aquatic habitats.

[Methane in cadaver blood--homicide by natural gas or postmortem formation?]

A man had a quarrel with his wife. Suddenly he collapsed and became cyanotic. The woman supposed him to be dead. Because she was afraid of familiar requital, she opened the gas-cock of the cooking-range to pretend a suicide; methane emitted. The autopsy revealed a fresh cardiac infarction. Postmortem chemical analysis established methane in the blood. The question was, whether the methane had any importance for the death. By experimental inhalation of a methane-air-mixture (3%) we could expose, that the methane concentration in postmortem blood didn't have any relevance for the death.

Reliability of head circumference measurements in preterm infants

PURPOSE

To describe and compare the intra- and interexaminer reliability of head circumference measurements obtained with paper and cloth tape measures.

METHOD

Two experienced neonatal nurses each obtained head circumference measurements using both paper and cloth tape measures twice each, from 49 clinically stable, preterm infants. The nurses were blind to their own and to each other's measurements. The order in which the measurements were obtained was randomized. The differences within and between examiners for cloth and paper tape measurements were described using mean absolute differences, standard deviation of net differences, technical error of measurement, minimal and maximal differences, percentage of differences 0.25 and 0.5 cm, and percentage of error.

RESULTS

Wilcoxon matched-pairs, signed-ranks tests demonstrated significantly greater intraexaminer reliability for measurements obtained with the paper tape for both of the nurses. Wilcoxon matched-pairs, signed-ranks tests also demonstrated significantly greater interexaminer reliability for measurements obtained with the paper tape for both the first and second measurement sets.

CONCLUSIONS

Intra- and interexaminer differences were consistently smaller when the examiners used paper tape measures.

[Ethanol content of Kefir water]

The question of the influence of kefir on blood-alcohol-level has been asked in a legal proceeding. The questioned recipe consisted of 21 water, 6 soup-spoons of kefir granules (about 120 g), 150 g sugar, 2 figs and one lemon. The consumption took place after two days of fermentation. Experimentally we found, that one liter of this kefir product may contain up to 38 g/l ethanol after 7 to 10 days. On the second day we measured up to 16 g/l ethanol. Our results may be import for expert appraisements concerning unability of driving.

Photorefractive properties of 4'-nitrobenzylidene-3-acetamino-4-methoxyaniline

Undoped single crystals of the organic electro-optic material 4'-nitrobenzylidene-3-acetamino-4-methoxyaniline were found to show photorefractive effects owing to light-induced charge separation. In two-wave-mixing experiments, beam-coupling gains as high as 2.2 cm(-1) and response times as low as 8 s at writing intensities of 130 mW/cm(2) were measured at a wavelength lambda = 514.5 nm. An analysis of the experimental data shows that the beam-coupling gain is limited by the electro-optic response of the material, while the response time is characterized by a large optical absorption and a low quantum efficiency for carrier generation.

[Iatrogenic methadone poisoning]

Two young drug addicts received in the course of their treatment a 10-fold overdose of methadone by error. One person died, the other was severely intoxicated but survived. The cause for the mistreatment was the unawareness of the medical personnel, that did not realize the change in concentration of the methadone stock solution from 0.1% to 1.0%, provided by the pharmacy. To prevent such mistakes in the future a change in labelling of the bottle giving directions for correct dosing is suggested.

Expression of recombinant TGF-beta 2(442) precursor and detection in BSC-40 cells

Analysis of cDNA clones encoding transforming growth factor (TGF)-beta 2 predicts two different precursor proteins derived by alternative mRNA splicing; a 414 amino acid precursor [TGF-beta 2(414)] and a 442 amino acid precursor [TGF-beta 2(442)]. The two proteins differ by a 28 amino acid insertion within the pro-region of TGF-beta 2(442). In order to characterize the TGF-beta 2-related proteins encoded by the TGF-beta 2(442) cDNA and determine whether it could, in fact, direct the synthesis of active growth factor, we have expressed this gene in Chinese hamster ovary (CHO) cells and, after amplification with methotrexate, obtained stable clones secreting TGF-beta 2(442). The TGF-beta 2 secreted by these cells was latent as acidification was necessary to detect optimal biological activity. In addition to mature TGF-beta 2, high molecular weight pro-region containing proteins were also secreted as analyzed by immunoblotting using site-specific anti-peptide antibodies. These proteins migrated differently than those secreted by CHO cells transfected with cDNA encoding TGF-beta 2(414), indicating that structural differences exist between the two complexes. An anti-peptide antiserum was produced in rabbits against the 28 amino acid insert region of TGF-beta 2(442). This sera was then used to detect the presence of TGF-beta 2(442) in serum-free media conditioned by BSC-40 cells. Since the TGF-beta 2(442) precursor is produced and secreted by a non-recombinant cell line, this suggests that it may play a physiological role in regulating the activity of TGF-beta 2.