The technology in cryotechnology

The process of freezing biological material at extremely low temperatures is known as cryopreservation. To ensure the preservation of cells and tissues over an extended period of time, low temperatures are applied since biological processes, including the biochemical ones, come to a halt under cryogenic conditions and thus it is possible to maintain their structural and functional integrity. The field of cryopreservation gained more prominence in the 20th century and emerged as an unavoidable technology for different applications such as cell therapy, tissue engineering, or assisted fertilization. In this work we provide an overview of various technologies in the field of cryotechnology with regard to the freezing, storage and thawing of living cells. The first part covers the freezing process, starting with cryoprotective agents regarding their protection mechanisms and compositions, passing by cryo-imaging, micro-fluidic systems, and the currently available freezing and biobanking equipment. The second part focusses on the thawing process as well as the hypothermic preservation for the short-term storage of biological materials and constructs. Doi.org/10.54680/fr23610110112.

Monitoring of freezing patterns within 3D collagen-hydroxyapatite scaffolds using infrared thermography

The importance of cryopreservation in tissue engineering is unceasingly increasing. Preparation, cryopreservation, and storage of tissue-engineered constructs (TECs) at an on-site location offer a convenient way for their clinical application and commercialization. Partial freezing initiated at high sub-zero temperatures using ice-nucleating agents (INAs) has recently been applied in organ cryopreservation. It is anticipated that this freezing technique may be efficient for the preservation of both scaffold mechanical properties and cell viability of TECs. Infrared thermography is an instrumental method to monitor INAs-mediated freezing of various biological entities. In this paper, porous collagen-hydroxyapatite (HAP) scaffolds were fabricated and characterized as model TECs, whereas infrared thermography was proposed as a method for monitoring the crystallization-related events on their partial freezing down to -25 °C. Intra- and interscaffold latent heat transmission were descriptively evaluated. Nucleation, freezing points as well as the degree of supercooling and duration of crystallization were calculated based on inspection of respective thermographic curves. Special consideration was given to the cryoprotective agent (CPA) composition (Snomax®, crude leaf extract from Hippophae rhamnoides, dimethyl sulfoxide (Me₂SO) and recombinant type-III antifreeze protein (AFP)) and freezing conditions ('in air' or 'in bulk CPA'). For CPAs without ice nucleation activity, thermographic measurements demonstrated that the supercooling was significantly milder in the case of scaffolds present in a CPA solution compared to that without them. This parameter (ΔT, °C) altered with the following tendency: 10 Me₂SO (2.90 ± 0.54 ('in air') vs. 7.71 ± 0.43 ('in bulk CPA', P < 0.0001)) and recombinant type-III AFP, 0.5 mg/ml (2.65 ± 0.59 ('in air') vs. 7.68 ± 0.34 ('in bulk CPA', P < 0.0001)). At the same time, in CPA solutions with ice nucleation activity the least degree of supercooling and the longest crystallization duration (Δt, min) for scaffolds frozen 'in air' were documented for crude leaf homogenate (CLH) from Hippophae rhamnoides (1.57 ± 0.37 °C and 21.86 ± 2.93 min compared to Snomax, 5 μg/ml (2.14 ± 0.33 °C and 23.09 ± 0.05), respectively). The paper offers evidence that infrared thermography provides insightful information for monitoring partial freezing events in TECs when using different freezing containers, CPAs and conditions. This may further TEC-specific cryopreservation and optimization of CPA compositions with slow-nucleating properties.

Impact of age, sex and body mass index on outcomes at four years after gastric banding

BACKGROUND

Adjustable gastric banding for weight reduction in severely obese persons allows reversible individualized restriction during postoperative follow-up. It is unknown whether preoperative age, sex and BMI might modulate treatment outcome.

METHODS

404 severely obese patients (79% women; age 42 +/- 0.5 years [mean +/- SEM]; BMI 42.1 +/- 0.2 kg/m2) completed 4-year follow-up after banding. Weight loss, complications, and Bariatric Analysis and Reporting Outcome System (BAROS) scores were recorded prospectively.

RESULTS

4 years after banding, younger (<50 years) women lost more weight than older (50 years) men (28.2 +/- 0.7% vs 19.4+/- 1.6%; P=0.001); older women and younger men lost similar weight. Patients with preoperative BMI >50 lost more weight than patients with BMI <35 (30.5 +/- 2.3% vs 22.8 +/- 2.6%; P=0.03). 22.3% of patients (n=90) had band system-related complications. Compared to women, men had more band leaks (7.0% vs 1.9%; P=0.007), and older men had more band slippages than younger men (8.4% vs 0.0%; P=0.035). Patients with preoperative BMI >50 were less likely than patients with BMI 35-40 or 40-50 to experience gastric complications (10.6%, 18.8%, 23.0%, respectively), but more likely to experience port/tube complications (15.8%, 2.4%, 7.9%, respectively; P<0.055). BAROS scores were different between men and women (P=0.05), and between younger and older people (P=0.001). Women and younger people were more likely than men and older people to score "very good" (P=0.03, P=0.001, respectively).

CONCLUSIONS

Adjustable gastric banding is an effective intermediate-term treatment for severe obesity. Preoperative age, sex, and BMI are important modulators of outcome and should be considered during preoperative evaluation.

Health-Related Quality of Life in Patients with Class II and Class III Obesity

BACKGROUND

Severe obesity may substantially impact quality of life. We estimated the health-related quality of life (HRQoL) in patients with class II and class III obesity, and explored the impact of patient characteristics and co-morbidities on quality of life.

METHODS

110 patients with BMI > or = 35 kg/m2 presenting for evaluation for bariatric surgery were asked to complete the EuroQoL questionnaire. Co-morbidities of the patients were recorded, including coxarthralgia, gonarthralgia, foot problems (pain and arthrosis), diabetes, dyslipidemia, hypertension, infertility, coronary heart disease, low back pain, peptic esophagitis, sleep apnea syndrome, urinary stress incontinence, and venous insufficiency. The determinants of HRQoL on the EQ-VAS score and EQ-5D index (both ranging from 0-100) were analyzed in a univariate and multivariate linear regression model.

RESULTS

The mean EQ-5D index (societal perspective) was 76, whereas the mean EQ-VAS (patient perspective) was 66 (P<0.0001). The mean number of comorbidities was 4.9 (range 0-11). Dyslipidemia (68%), low back pain (63%) and venous insufficiency (57%) were the 3 most frequent co-morbidities. However, low back pain (beta= -11.4) and foot problems (beta= -8.5) were significantly associated with a reduction in the EQ-VAS score, whereas low back pain (beta= -8.4) and coronary heart disease (beta= -24.9) were significantly associated with a reduction in the EQ-5D index.

CONCLUSION

The number and type of co-morbidities determine HRQoL in patients with severe obesity. Within our study population, a higher BMI, however, was not associated with a lower quality of life.