Tityus: a forgotten myth of liver regeneration

Turning points in the practice of liver surgery: A historical review

The history of liver surgery is a tale of progressive resolution of issues presenting one after another from ancient times to the present days when dealing with liver ailments. The perfect knowledge of human liver anatomy and physiology and the development of a proper liver resective surgery require time and huge efforts and, mostly, the study and research of giants of their own times, whose names are forever associated with anatomical landmarks, thorough descriptions, and surgical approaches. The control of parenchymal bleeding after trauma and during resection is the second issue that surgeons have to resolve. A good knowledge of intra and extrahepatic vascular anatomy is a necessary condition to develop techniques of vascular control, paving the way to liver transplantation. Last but not least, the issue of residual liver function after resection requires advanced techniques of volume redistribution through redirection of blood inflow. These are the same problems any young surgeon would face when approaching liver surgery for the first time. Therefore, obtaining a wide picture of historical evolution of liver surgery could be a great starting point to serve as an example and a guide.

The prothrombotic tendency of metabolic-associated fatty liver disease

Our understanding of the function of the liver has evolved over the centuries. Early theories proposing that the liver could be used to divine the future have been superseded by our current knowledge of the importance of the liver in processes such as digestion and detoxification. Similarly, although liver disease was previously associated with only an increased risk of bleeding, there is now a substantial body of evidence demonstrating an increased thrombotic potential in patients with this disease. Metabolic-associated fatty liver disease (MAFLD) is increasing in frequency and is likely to overtake alcoholic liver disease as the primary indication for liver transplant in the future. In this review, we discuss the evidence linking liver disease, and MAFLD in particular, with arterial and venous thromboembolic disease. We review the safety and efficacy of anticoagulation in advanced liver disease and consider whether antithrombotic agents could slow or halt the progression of fibrosis in MAFLD.

Population Dynamics, Plasma Cytokines and Platelet Centrifugation: Technical and Sociodemographic Aspects of 'Ovarian Rejuvenation'

While advanced reproductive technologies have attained remarkable increases in sophistication, success, and availability since the 1980s, clinicians always meet a therapeutic impasse when the ovarian reserve reaches exhaustion. Irrespective of fertility aspirations, the decline in and eventual collapse of ovarian estrogen output means that menopause arrives with tremendous physiologic changes and reduced overall productivity. Because more women are gaining in longevity or delaying the age at pregnancy, the number of affected patients has never been larger. As concerns regarding standard hormone replacement therapy and the limitations of IVF are confronted, a workable path to enable primordial germ cell recruitment and de novo oocyte development would be welcome. Proof-of-concept case reports and clinical studies on autologous activated platelet-rich plasma (PRP) or its condensed cytokine derivatives suggest a way to facilitate these goals. However, ovarian PRP faces vexing challenges that place 'ovarian rejuvenation' under caution as it enters this therapeutic space. Here, we review key features of experimental human ovarian stem cell isolation/handling and reaffirm the need to harmonize laboratory protocols. Recognizing the regenerative science borrowed from other disciplines, specimen centrifugation, platelet processing, and condensed plasma cytokine enrichment are highlighted here. As the refinement of this rejuvenation approach would promise to reprogram adult ovarian physiology, the disruption of established treatment paradigms for infertility, menopause, and perhaps overall women's health seems likely. Emerging roles in reproductive biology and clinical practice are thus placed in a broader social and demographic context.

The Influence of Interdisciplinary Work towards Advancing Knowledge on Human Liver Physiology

The knowledge accumulated throughout the years about liver regeneration has allowed a better understanding of normal liver physiology, by reconstructing the sequence of steps that this organ follows when it must rebuild itself after being injured. The scientific community has used several interdisciplinary approaches searching to improve liver regeneration and, therefore, human health. Here, we provide a brief history of the milestones that have advanced liver surgery, and review some of the new insights offered by the interdisciplinary work using animals, in vitro models, tissue engineering, or mathematical models to help advance the knowledge on liver regeneration. We also present several of the main approaches currently available aiming at providing liver support and overcoming organ shortage and we conclude with some of the challenges found in clinical practice and the ethical issues that have concomitantly emerged with the use of those approaches.

Long-term Outcome of Autologous Hematopoietic Stem Cell Infusion in Cirrhosis: Waning Effect over Time

Background and Aims: Long-term data on cell-based therapies, including hematopoietic stem cell infusion in cirrhosis, are sparse and lacking. Methods: Patients with cirrhosis of non-viral etiology received either standard-of-care (n = 23) or autologous CD34+ cell infusion through the hepatic artery (n = 22). Study patients received granulocyte colony-stimulating factor (commonly known as G-CSF) injections at 520 µgm per day for 3 days, followed by leukapheresis and CD34+ cell infusion into the hepatic artery. The Control group received standard-of-care treatment. Results: Mean CD34+ cell count on the third day of G-CSF injection was 27.00 ± 20.43 cells/µL 81.84 ± 11.99 viability and purity of 80-90%. Significant improvement in the model of end-stage liver disease (commonly known as MELD) score (15.75 ± 5.13 vs. 19.94 ± 6.68, p = 0.04) was noted at end of 3 months and 1 year (15.5 ± 5.3 vs. 19.8 ± 6.4, p = 0.04) but was not statistically different at end of the second (17.2 ± 5.5 vs. 20.3 ± 6.8, p = 0.17) and third-year (18.4 ± 6.1 vs. 21.3 ± 6.4, p = 0.25). No difference in mortality (6/23 vs. 5/23) was noted. Conclusions: Autologous CD34+ cell infusion effectively improved liver function and MELD score up to 1 year but the sustained benefit was not maintained at the end of 3 years, possibly due to ongoing progression of the underlying disease.

"I Miss My Liver." Nonmedical Sources in the History of Hepatocentrism

Hepatocentrism was a medical doctrine that considered the liver the center of the whole human being. It originated in ancient populations (Mesopotamic civilization) and persisted in Western countries until the seventeenth century. Hidden references to hepatocentrism may be found in artistic representations and literary works, from the myth of Prometheus in the Greco-Roman world to the crucifixion iconography throughout the Middle Ages. In the mid-1600s, fundamental discoveries irrefutably demonstrated the central role of the heart in human physiology, which laid the foundations for creating cardiocentrism, shifting the life's center from the liver to the heart. The advent of cardiocentrism immediately restricted the importance given to the liver, favoring the heart in the fine arts. Nevertheless, the liver maintained its importance in literature and popular belief as is evidenced by the widely acclaimed literary texts "Snow White" by the Brothers Grimm, "Moby Dick" by Herman Melville, and "Ode to the Liver" by Pablo Neruda. Our aim is to analyze the most significant artistic representations and literary works that contain references to hepatocentrism, evaluating the changing ideas and beliefs regarding the role and function of the liver throughout history. We want to underline the tight relationship between art and medicine; fine art and literature could be a valuable source for understanding the history of hepatology. (Hepatology Communications 2018; 00:000-000).

Hyperplasia vs hypertrophy in tissue regeneration after extensive liver resection

AIM

To address to what extent hypertrophy and hyperplasia contribute to liver mass restoration after major tissue loss.

METHODS

The ability of the liver to regenerate is remarkable on both clinical and biological grounds. Basic mechanisms underlying this process have been intensively investigated. However, it is still debated to what extent hypertrophy and hyperplasia contribute to liver mass restoration after major tissue loss. We addressed this issue using a genetically tagged system. We were able to follow the fate of single transplanted hepatocytes during the regenerative response elicited by 2/3 partial surgical hepatectomy (PH) in rats. Clusters of transplanted cells were 3D reconstructed and their size distribution was evaluated over time after PH.

RESULTS

Liver size and liver DNA content were largely recovered 10 d post-PH, as expected (e.g., total DNA/liver/100 g b.w. was 6.37 ± 0.21 before PH and returned to 6.10 ± 0.36 10 d after PH). Data indicated that about 2/3 of the original residual hepatocytes entered S-phase in response to PH. Analysis of cluster size distribution at 24, 48, 96 h and 10 d after PH revealed that about half of the remnant hepatocytes completed at least 2 cell cycles. Average size of hepatocytes increased at 24 h (248.50 μm² ± 7.82 μm², P = 0.0015), but returned to control values throughout the regenerative process (up to 10 d post-PH, 197.9 μm² ± 6.44 μm², P = 0.11). A sizeable fraction of the remnant hepatocyte population does not participate actively in tissue mass restoration.

CONCLUSION

Hyperplasia stands as the major mechanism contributing to liver mass restoration after PH, with hypertrophy playing a transient role in the process.

Liver regeneration: immunohistochemical study of intrinsic hepatic innervation after partial hepatectomy in rats

Background

We examined the intrinsic hepatic innervation after partial hepatectomy (PH) in rats and the presence and pattern of neural sprouting in regenerating liver.

Methods

Male Wistar rats (age 9–13 weeks-w, weight 204-356 g), were submitted to two-thirds PH. Rats were sacrificed at postoperative days (d) 1, 3, 5, 7, at 2 and 4 w, and at 3 and 6 months (m) (6–7 animals/group, control group n = 4). Immunohistochemistry for the pan-neural marker protein gene product 9.5 (PGP9.5) and growth-associated protein 43 (GAP-43), a marker of regenerating nerve axons, was performed on tissue sections from the R1 lobe of the regenerating liver. Portal tracts (PTs) with immunoreactive fibers were counted in each section and computer-assisted morphometric analysis (Image Pro Plus) was used to measure nerve fiber density (number of immuno-positive nerve fibers/mm² (40x)).

Results

Immunoreactivity for PGP9.5 was positive in all groups. The number of PGP9.5 (+) nerve fibers decreased from 0.32 +/− 0.12 (control group) to 0.18 +/− 0.09 (1d post-PH group), and gradually increased reaching pre-PH levels at 6 m (0.3 +/− 0.01). In contrast, immunoreactivity for GAP-43 was observed at 5d post-PH, and GAP-43 (+) PTs percentage increased thereafter with a peak at 3 m post-PH. GAP-43 (+) nerve fiber density increased gradually from 5d (0.05 +/− 0.06) with a peak at 3 m post-PH (0.21 +/− 0.027). At 6 m post-PH, immunoreactivity for GAP-43 was not detectable.

Conclusions

Following PH in rats: 1) nerve fiber density in portal tracts decreases temporarily, and 2) neural sprouting in the regenerating liver lobes starts at 5d, reaches peak levels at 3 m and disappears at 6 m post-PH, indicating that the increase in hepatic mass after PH provides an adequate stimulus for the sprouting process.

Transcriptome temporal and functional analysis of liver regeneration termination

Decades of liver regeneration studies still left the termination phase least elucidated. However regeneration ending mechanisms are clinicaly relevant. We aimed to analyse the timing and transcriptional control of the latest phase of liver regeneration, both controversial. Male Wistar rats were subjected to 2/3 partial hepatectomy with recovery lasting from 1 to 14 days. Time-series microarray data were assessed by innovative combination of hierarchical clustering and principal component analysis and validated by real-time RT-PCR. Hierarchical clustering and principal component analysis in agreement distinguished three temporal phases of liver regeneration. We found 359 genes specifically altered during late phase regeneration. Gene enrichment analysis and manual review of microarray data suggested five pathways worth further study: PPAR signalling pathway; lipid metabolism; complement, coagulation and fibrinolytic cascades; ECM remodelling and xenobiotic biotransformation. Microarray findings pertinent for termination phase were substantiated by real-time RT-PCR. In conclusion, transcriptional profiling mapped late phase of liver regeneration beyond 5(th) day of recovery and revealed 5 pathways specifically acting at this time. Inclusion of longer post-surgery intervals brought improved coverage of regeneration time dynamics and is advisable for further works. Investigation into the workings of suggested pathways might prove helpful in preventing and managing liver tumours.

"The city of Hepar": rituals, gastronomy, and politics at the origins of the modern names for the liver

Medical etymology sometimes provides unexpected information about health concepts and medical practice in different times and cultures. We conducted an etymological analysis of the terms used to indicate "liver" in Germanic and Romance languages. The Greek word "hèpar" was originally connected to the concept of "pleasure", showing that in antiquity the liver was considered to be the seat of soul and human feelings. In Romance languages, the Latin term "ficatum" was linked to the ancient practice of fattening geese with figs (ficus in Latin) to make their livers more delicious. This relationship between the liver, fat, and carbohydrates seems to indicate that ancient gourmets had clear knowledge of the nutritional mechanisms underlying "fatty liver" in animals. On the other hand, the Germanic term "lifere" was initially connected to "life", underscoring the relation of the liver to health and existence. In the Early Modern Age, the liver became a recurring image in political reflection, especially within the Elizabethan tradition of the body politic, where the king was frequently described as the "liver" of his country. Finally, the liver was used to indicate courage, or the lack of it: some modern French and English idiomatic expressions derive from the ancient belief that people who had no blood in their liver ("lily-livered") would thus be cowards or betrayers.

CXC chemokine signaling in the liver: impact on repair and regeneration

The process of liver repair and regeneration following hepatic injury is complex and relies on a temporally coordinated integration of several key signaling pathways. Pathways activated by members of the CXC family of chemokines play important roles in the mechanisms of liver repair and regeneration through their effects on hepatocytes. However, little is known about the signaling pathways used by CXC chemokine receptors in hepatocytes. Here we review our current understanding of the pathways involved in both CXC chemokine receptor signaling in other cell types, most notably neutrophils, and similar pathways operant during hepatocyte proliferation/liver regeneration to formulate a basis for the function of CXC chemokine receptor signaling in hepatocytes.