The paper below is a comment by Hiroki Yokota on another study about how a mechanism called dynamic hydraulic stimulation might be similar to LSJL. Note that although Hiroki Yokota is involved in LSJL, Ping Zhang is the one more focused on LSJL for length.
Dynamic muscle loading and mechanotransduction
"dynamic hydraulic stimulation (DHS), applies noninvasive dynamic pressure (30 mm Hg static + 30 mm Hg dynamic) to the skin and muscle tissues that surround the tibia of a hindlimb-suspended rat for 20 min per day, 5 days per week. After 4 weeks of DHS treatment, bone volume fraction and bone formation rate were increased by 83% and 190%, respectively, compared to their non-stimulated, tail-suspended counterparts."<-Can this increase height?
"Instead of applying axial loads, which are more closely linked to routine physical activities, DHS employs lateral loads"<-Like LSJL. "JL to a mouse knee alters ImP"
"DHS applies loads to the diaphysis by constricting circumferentially, while JL applies loads to the epiphysis and metaphysis by compressing at two confined regions"
"The working hypothesis of DHS' mechanism of action consists of three major steps: alterations in ImP, induction of interstitial fluid flow (IFF), and mechanosensing by osteocytes followed by activation of Wnt signaling in osteoblasts"<-Same as those with LSJL except we also believe that that LSJL increases pressure in the epiphysis to induce chondrogenic differentiation.
"the effect of the increased ImP is not confined to the loading site but is distributed throughout the intramedullary cavity"<-and should be distributed to the epiphysis as well.
"IFF should be able to generate the amount of energy equivalent to one ATP molecule or ~ 10kT (the energy generated by one ATP molecule is approximately 10 times larger than kT)"
"in order to move part of a mechanosensing molecule by several nanometers, 10kT of energy can generate a force of ~ 10 pN. This amount of force corresponds to a surface area of 10 μm2 under shear stress at 1 Pa (10 dyn/cm2). In order for a single osteocyte process (~ 20 μm long, 50–400 nm in diameter) to receive 10 pN and move a molecular sensor by several nanometers, it is plausible that there is an amplification mechanism "
Here's the study on Dynamic Hydraulic Flow the LSJL like stimulus:
Dynamic hydraulic flow stimulation on mitigation of trabecular bone loss in a rat functional disuse model.
"To elevate in vivo oscillatory BFF[Bone Fluid Flow] using ImP[Intramedullary Pressure], a dynamic hydraulic stimulation (DHS) approach was developed. The objective of this study was to evaluate the effects of DHS on mitigation of bone loss and structural alteration in a rat hindlimb suspension (HLS) functional disuse model. Sixty-one 5-month old female Sprague-Dawley rats were divided into five groups: 1) baseline control, 2) age-matched control, 3) HLS, 4) HLS+static loading, and 5) HLS+DHS. Hydraulic flow stimulation was carried out daily on a "10min on-5min off-10min on" loading regime, 5days/week, for a total of 4weeks in the tibial region. The metaphyseal trabecular regions of the proximal tibiae were analyzed using μCT and histomorphometry. Four weeks of HLS resulted in a significant loss of trabecular bone, leading to structural deterioration. HLS with static loading alone was not sufficient to attenuate the bone loss. Bone quantity and microarchitecture were significantly improved by applying DHS loading, resulting increase of 83% in bone volume fraction, 25% in trabecular number and mitigation of -26% in trabecular separation compared to HLS control. Histomorphometry analysis on trabecular mineralization coincided with the μCT analysis, in which DHS loading yielded increases of 34% in histomorphometric BV/TV, 121% in MS/BS, 190% in BFR/BS and 146% in BFR/BV, compared to the HLS control."
Here's a picture of the device:
"DHS was achieved through a costumer design inflatable cuff placed around the right hindlimb of the tibia. The stimulation cuff was connected to an oscillatory actuator-driven syringe, a force-controlled syringe, and a pressure sensor"<-So basically like some sort of device like the inflatable blood pressure detectors.
"The force-controlled syringe was included to maintain the static pressure, and the pressure sensor was used to monitor the hydraulic pressure throughout the procedure to maintain baseline static pressure."
"veins within skeletal muscle are compressed upon DHS and thus increasing the arteriovenous pressure gradient and promoting blood flow to the capillary bed. The pressure gradient in the muscle vasculature may be relayed to the nutrient vessels in bone, further increasing ImP and inducing fluid flow in bone"
It should be noted that no evidence of height growth was given in the study(although they didn't look for it). However, the method seems to operate similarly to LSJL and may too be able to stimulate mesenchymal chondrogenesis by an increase in hydrostatic pressure in epiphyseal bone marrow or perhaps by cyclical shear strain of cells inducing intracellular calcium signaling inducing chondrogenic differentiation in MSCs.
Note that unlike a blood pressure cuff this was attached to the joint of the bone rather than the median of the bone.
Some type of blood pressure cuff around the joint area may eventually be a method to increase height.
Here's the Lab page for the lead scientist Yi-Xian Qin.
Intramedullary pressure and matrix strain induced by oscillatory skeletal muscle stimulation and its potential in adaptation
"Intramedullary pressure (ImP) and low-level bone strain induced by oscillatory muscle stimulation (MS) has the potential to mitigate bone loss induced by disuse osteopenia, i.e., hindlimb suspension (HLS). To test this hypothesis, we evaluated (a) MS-induced ImP and bone strain as function of stimulation frequency and (b) the adaptive responses to functional disuse, and disuse plus 1 and 20 Hz stimulation in vivo. Femoral ImP and bone strain generated by MS were measured in the frequencies of 1–100 Hz in four rats. Forty retired breeder rats were used for the in vivo HLS study. The quadriceps muscle was stimulated at frequencies of 1 and 20 Hz, 10 min/d for four weeks. The metaphyseal trabecular bone quantity and microstructure at the distal femur were evaluated using μCT, while bone formation indices were analyzed using histomorphometric technique. Oscillatory MS generated a maximum ImP of 45±9 mmHg at 20 Hz and produced a maximum matrix strain of 128±19 με at 10 Hz. Our analyses from the in vivo study showed that MS at 20 Hz was able to attenuate trabecular bone loss and partially maintain the microstructure induced by HLS. Conversely, there was no evidence of an adaptive effect of stimulation at 1 Hz on disused skeleton. The results suggested that oscillatory MS regulates fluid dynamics and mechanical strain in bone, which serves as a critical mediator of adaptation. These results clearly demonstrated the ability of MS in attenuating bone loss from the disuse osteopenia, which may hold potential in mitigating skeletal degradation imposed by conditions of disuse, and may serve as a biomechanical intervention in clinic application."
"Skeletal muscle contraction can increase blood flow within musculoskeletal tissues and generate bone strain within the physiological range"<-If we get more data on oscillatory muscle stimulation we can see whether the lengthening effects of LSJL are due intermedullary pressure or blood flow increase or something else.
"Four 6–9 months old Sprague Dawley retired breeder rats with a mean body weight of 387±41 g"
Intramedullary pressure and matrix strain induced by oscillatory skeletal muscle stimulation and its potential in adaptation.
Intramedullary pressure and matrix strain induced by oscillatory skeletal muscle stimulation and its potential in adaptation.
"We evaluated (a) MS[Matrix Strain]-induced ImP[Intramedullary Pressure] and bone strain as function of stimulation frequency and (b) the adaptive responses to functional disuse, and disuse plus 1 and 20 Hz stimulation in vivo. Femoral ImP and bone strain generated by MS were measured in the frequencies of 1-100 Hz in four rats. Forty retired breeder rats were used for the in vivo HLS study. The quadriceps muscle was stimulated at frequencies of 1 and 20 Hz, 10 min/d for four weeks. The metaphyseal trabecular bone quantity and microstructure at the distal femur were evaluated using microCT, while bone formation indices were analyzed using histomorphometric technique. Oscillatory MS generated a maximum ImP of 45+/-9 mmHg at 20 Hz{According to an LSJL study, the pressure increase at 4N was 120Pa which is 0.9 mmHg. Note though that the baseline pressure was 1290 Pa or 9.5mmHg which is much less than 45mmHg although this may be due to rat differences or it could indicate that the LSJL lengthening response is not due to pressure changes} and produced a maximum matrix strain of 128+/-19 microepsilon at 10 Hz. Our analyses from the in vivo study showed that MS at 20 Hz was able to attenuate trabecular bone loss and partially maintain the microstructure induced by HLS. Conversely, there was no evidence of an adaptive effect of stimulation at 1 Hz on disused skeleton. The results suggested that oscillatory MS regulates fluid dynamics and mechanical strain in bone, which serves as a critical mediator of adaptation."
"by inducing a 20 Hz of fluid pressure into the marrow cavity of turkey ulna, the formation of periosteal and endosteal new bone was augmented at the cortex"<-what would the effect be in the epiphysis?
"6 to 9-months-old Sprague Dawley retired breeder rats with a mean body weight of 387g ± 41g "
"Normal heart beat generated approximately 5 mmHg of ImP in the femur at a frequency of 5.37±0.35 Hz. The ImP value (peak-peak) was increased by dynamic MS at 5, 10, 15, 20, 30, and 40 Hz"
"The MS generated ImP values of 17.4±6.2, 24±5.4, 37.5±11.0, 26.3±11.1, and 3.7±1.5 mmHg at frequencies of 1, 5, 10, 40, and 100 Hz, respectively."
"The MS generated femoral matrix strains of 61.8±6.2, 87.5±5.1, 128.4±19.2, 78.3±6.8, 18.7±1.3, and 10.1±1.8 με at frequencies of 1, 5, 10, 20, 40, and 100 Hz"
"According to a muscle pump hypothesis, an arteriovenous pressure gradient enhances muscle perfusion. This process may in turn increase the hydraulic pressure in skeletal nutrient vessels and amplify the capillary filtration in bone tissue"
Mechanical signals as anabolic agents in bone.
"Large, intense challenges to the skeleton are generally presumed to be the most osteogenic, but brief exposure to mechanical signals of high frequency and extremely low intensity, several orders of magnitude below those that arise during strenuous activity, have been shown to provide a significant anabolic stimulus to bone. Along with positively influencing osteoblast and osteocyte activity, these low-magnitude mechanical signals bias MSC differentiation towards osteoblastogenesis and away from adipogenesis{but what of towards chondrogenesis?}."
"Over the daily course of functional challenges, bone will be subjected to exceptionally few high-strain (2,000–3,000 microstrain), low-frequency (1–3 Hz, or cycles per second) events, but to a persistent barrage of low-strain (<5 microstrain), high-frequency events (10–50 Hz), stemming from muscle contractions engaged to retain posture"
"The PPARγ transcription factor, when absent or present as a single copy, facilitates osteogenesis at least partly through enhanced canonical Wnt signaling"<-So maybe adipose stem cells are more prone to chondrogenesis than mesenchymal stem cells?
"LMMS[Low Magnitude Mechanical Stimulation] treatment also resulted in a 46% increase in the size of the MSC pool"<-which would also help with chondrogenesis"
" In vitro experimentation with osteocyte-like cells also shows that pulsating fluid flow increases the expression of proteins that function in the canonical Wnt pathways."
"activation and nuclear translocation of β-catenin occurs in MSCs within minutes of the mechanical stimulus."<-So maybe a Beta-Catenin inhibitior will help with LSJL chondroinduction.
Dynamic skeletal muscle stimulation and its potential in bone adaptation.
"venous pressure is directly related to ImP and interstitial fluid flow."
"Adult Sprague Dawley retired breeder rats with a mean body weight of 387g±41g"
"the ImP reached a maximum value of 45±9.3 mmHg (peak-peak) at 20 Hz"
"Fluid movement generated by the intramedullary pressure (ImP) provides a source for pressure gradient in bone. Dynamic ImP may alter the blood flow within nutrient vessel adjacent to bone and directly connected to the marrow cavity, further initiating nutrient vessel adaptation. Oscillatory ImP can mediate the blood flow in the skeletal nutrient vessels and trigger vasculature remodeling. The objective of this study was then to evaluate the vasculature remodeling induced by dynamic ImP stimulation as a function of ImP frequency.
Using an avian model, dynamics physiological fluid ImP (70 mmHg, peak-peak) was applied in the marrow cavity of the left ulna at either 3 Hz or 30 Hz, 10 minutes/day, 5 days/week for 3 or 4 weeks. The histomorphometric measurements of the principal nutrient arteries were done to quantify the arterial wall area, lumen area, wall thickness, and smooth muscle cell layer numbers for comparison.
The preliminary results indicated that the acute cyclic ImP stimuli can significantly enlarge the nutrient arterial wall area up to 50%, wall thickness up to 20%, and smooth muscle cell layer numbers up to 37%. In addition, 3-week of acute stimulation was sufficient to alter the arterial structural properties, i.e., increase of arterial wall area, whereas 4-week of loading showed only minimal changes regardless of the loading frequency."
So conditioning response may begin after the end of three weeks.
" The principal nutrient artery pierces the diaphysis at the nutrient foramen, penetrates through the cortex and branch proximally and distally within the medullary cavity to the metaphyseal regions, supplying the inner two-thirds of the cortex"<-How do the nutrient arteries effect the epiphysis? This could be part of the difference between LSJL and muscle stimulation. In muscle stimulation the main vessel generating pressure is at the center of the bone whereas the LSJL pressure gradient begins at the end of the bone.
Here's some information on the epiphyseal artery from the orthopedics textbook:
"Epiphyseal artery:
- in femoral and radial heads which are almost entirely covered by cartilage,
- vessels enter in region between articular cartilage & growth-plate cartilage, and hence, the blood supply is tenuous[weak];
- in other regions, the epiphysis has openings that permit passage of large number of vessels into and out of the ossification centers;
- growth plate itself is avascular & receives nutrition from 2 sources;
- epiphyseal vessels that supply resting, germinal, proliferating, and upper hypertrophic cell layers by diffusion
- metaphyseal vessels that supply zone of provisional calcification;
- in young child, epiphyseal vessels are separated from metaphyseal vessels, but following growth arrest of the cartilage plate, there is
an extensive anastomoses between epiphyseal vessels, metaphyseal vessels, & terminal branches of Nutrient Artery{unification};
- obliteration of epiphyseal blood supply results in necrosis of epiphysis & deprives deeper cartilage cells of growth plate of their nutrition;
- longitudinal growth ceases, &, if collateral circulation is not quickly restored, permanent closure of epiphyseal plate occurs;
- epiphyseal vessels are responsible for permitting longitudinal growth to occur, whereas metaphyseal vessels nourish osteoprogenitor cells, which lay down bone on cartilage matrix"
Maybe by loading from the epiphysis downward the body is tricked into thinking the growth plate epiphyseal vessels are there.
A study with possible insights on adult epiphyseal vascularization:
Vascularisation of the head of the radius in the adult.
"The epiphyseal vascularisation of the proximal end of the radius was studied by dissection and diaphanisation techniques. The main extra-osseous supply is derived from epiphyseo-metaphyseal arteries given off by the recurrent radial a. and the first collateral of the ulnar a. These, to the number of three or four, anastomose together in a peri-cervical arterial circle continuous with the periosteal vessels of the shaft. From the proximal part of this network there arise three main intra-epiphyseal branches, which traverse the head, but nearly the entire periphery of the osteochondral junction is the site of small periosteal branches penetrating the head, though to no great depth. When the head of the radius is fractured, the commonest displacement is posterolateral, and the main vessel-bearing periosteal layer probably remains intact."
There are some blood vessels going through the epiphysis but mostly they are around the neck.
Here's epiphyseal vascularization in younger individuals:
"The vascular pattern of newborn and early postnatal epiphyseal and physeal cartilage is integral to long bone development and differs from later postnatal patterns"
"Transphyseal vessels were seen in each epiphysis continuous from the epiphysis to the metaphysis or were present within the physis traversing the proliferating and hypertrophic cell zones. Histologic sections showed vessels from the perichondrium continuous with those of the epiphyseal cartilage canals at proximal humeral, distal femoral, and metatarsal epiphyses. Serial sections showed vascular buds and connective tissue cells lying in indentations at the periphery of and present within the epiphyseal cartilage. Autoradiographic studies showed extensive labeling of vessel wall cells and surrounding connective tissue cells of the cartilage canals (a) within the epiphyseal cartilage, (b) traversing the physis, and (c) within the epiphyseal cartilage but continuous with the perichondrial vessels. The labeling was always far more extensive than in the surrounding chondrocytes and was always present throughout the entire extent of the canals. In conclusion, the cell labeling activity strongly supports an active dynamic phenomenon underlying the vascularization of epiphyseal and physeal cartilage."
Here's a diagram:
In the infant growth cartilage manages to form regardless of the presence of arteries and the epiphyseal arteries are still present in the adult.
hey Tyler, do you think its possible that you'll make a bit more decent video of where to put the Clamp on your knee? You might admit that its impossibe to figure it out from your videos. thanks!
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