Between-subject variability and within-subject reliability of the human eye-movement response to bilateral galvanic (DC) vestibular stimulation

Recent studies have shown that responses to surface galvanic vestibular stimulation (GVS) show substantial interindividual variation. Between-subject variability may be due to individual differences between subjects, or to the poor reliability of the test, or to differences in test details, or to host factors. The aim of the present study was to compare variability between and within subjects in binocular 3-D eye-movement responses to long-duration, maintained, large-amplitude, bilateral, bipolar, surface GVS. Subjects were seated and restrained, and in one condition fixated a small, centrally located visual target; in the other condition, testing was carried out in complete darkness. Surface GVS of 5 mA, with a rectangular waveform was delivered bilaterally for 5 min while eye movements were measured using computerised video-oculography (VTM). In the first experiment, ten subjects participated in both conditions in one session, and in the second experiment, two subjects participated in both conditions for a total of five repeated sessions. The stimulation was well tolerated by all subjects and produced a change in torsional position with the upper pole of both eyes rolling towards the anode and away from the cathode in all subjects in both conditions. Although little vertical nystagmus was evident in either condition, most subjects showed relatively strong horizontal nystagmus (slow phases towards the anode) in darkness. This study confirms previous observations that the torsional response to GVS is highly variable between subjects, whilst also showing for the first time that eye-movement responses to GVS show good within-subject repeatability. This study also demonstrates considerable between-subject variability in the relative ratios of response components (torsional and horizontal nystagmus, torsional position), whereas the relatively small within-subject variability can be characterised more by changes in the overall amplitude of the eye-movement response. Subjects show idiosyncratic oculomotor response patterns to GVS, varying slightly in absolute magnitude between sessions. Thus, GVS may be a more reliable stimulus than may have been anticipated from the literature.     

Maintained ocular torsion produced by bilateral and unilateral galvanic (DC) vestibular stimulation in humans

 This study was designed to measure ocular movements evoked by galvanic (DC) stimulation using computerised video-oculography. Long duration (>30 s) galvanic vestibular stimulation at currents of up to 5 mA through large-area surface electrodes over the mastoid processes causes maintained changes in the ocular torsional position of both eyes in healthy human subjects. With the subject seated and the head held firmly, torsion was measured by a computer-based image-processing system (VTM). Torsion was recorded in darkness, with or without a single fixation point. With bilateral stimulation, the upper poles of both eyes always torted away from the side of cathode placement and toward the anode. For unilateral stimulation, torsion was directed away from the cathode or toward the anode. The magnitude of ocular torsion was dependent on current strength: with bilateral stimulation the peak torsion was on average 2.88° for 5-mA current intensity compared with 1.58° for 3 mA. A smaller amplitude of torsion was obtained for unilateral stimulation. The average peak torsion was the same for both eyes for all forms of stimulation. Our findings indicate that low-intensity galvanic stimulation evokes ocular torsion in normal subjects, an effect which is consistent with an action on otolith afferents. Received: 27 March 1998 / Accepted: 23 June 1998     

Orientation of the body response to galvanic stimulation as a function of the inter-vestibular imbalance

We proposed to study and quantify the anteroposterior component, on top of the lateral one, of the body sway induced by different configurations of galvanic vestibular stimulation (GVS) in order to advance the understanding of the orientation of the response. Four stimulation configurations were used in two separate experiments: monaural, binaural, and opposite double monaural in the first experiment (11 subjects); monaural and double monaural in the second (13 subjects). The postural response of the subjects, standing with their eyes closed, to the stimulus (0.6 mA, 4 s) was assessed by measuring the displacement of the center of pressure (CoP) using a force platform. As usual, binaural GVS induced a strictly lateral deviation of the center of pressure. The opposite double monaural condition induced a similar lateral sway to that obtained in the binaural mode, although with a very different stimulation configuration. Monaural GVS induced an oblique, stereotyped deviation in each subject. The anteroposterior component comprised a forward deviation when the anode was on the forehead and a backward deviation when the anode was on the mastoid. The lateral component, directed towards the anode as in the binaural design, was twice as large in the binaural than in the monaural mode. The second experiment showed that double monaural stimulation elicited an anteroposterior deviation (backwards when the anode was on the mastoids and forwards when it was on the forehead) that was equivalent to the addition of two complementary monaural configurations. The present results show that monaural stimulation activates one side of the vestibular apparatus and induces reproducible, stereotyped deviations of the CoP in both the anteroposterior and lateral plane. Secondly, binaural GVS appears to result from the addition of two complementary monaural stimulations. Lateral components of the response to each stimulation, being in the same direction, are summed, whilst anteroposterior components, being in opposite directions, cancel each other out. The opposite happens when both labyrinths are polarized in the same way, as in the double monaural configuration. We suggest that the orientation of the response to GVS is a function of the imbalance between right and left vestibular polarization, rather than a function of the actual position of the electrodes.     

From head orientation to hand control: evidence of both neck and vestibular involvement in hand drawing

This research investigated the effect of head to trunk relation in a sensorimotor drawing task. In the first experiment, seated participants were asked to reproduce with eyes closed geometric shapes (square or diamond) with the tip of their right index finger in the frontoparallel plane. Their head was either aligned with the trunk or tilted 25° towards the left or right shoulder. Results showed that drawings were subjected to an overall rotation of a few degrees in the opposite direction to the tilt. In two subsequent experiments, the respective contribution of both otoliths and neck receptors to this head tilt effect was investigated. In Experiment 2, seated participants kept their head straight but were subjected to 2.5 mA vestibular galvanic stimulation (GVS). Results indicated that GVS induced a small but significant deviation of the drawings towards the anode. Finally, in Experiment 3, subjects performed the drawing task either seated upright (seated condition) or lying on their back (supine condition). Unlike in the seated condition, tilting the head towards the shoulders in a supine posture does not modulate afferents from the otolith stimulation and therefore mainly stimulates neck receptors. Head tilt induced rotations of hand-drawn reproductions in both seated and supine conditions, suggesting a significant contribution of neck afferents in the control of hand motion in space in the absence of vision. Overall the data provided evidence for a strong head-hand linkage during kinaesthetically guided drawing movements. Electronic Publication     

The human horizontal vestibulo-ocular reflex in response to high-acceleration stimulation before and after unilateral vestibular neurectomy

Summary The normal horizontal vestibulo-ocular reflex (HVOR) is largely generated by simultaneous stimulation of the two horizontal semicircular canals (HSCCs). To determine the dynamics of the HVOR when it is generated by only one HSCC, compensatory eye movements in response to a novel vestibular stimulus were measured using magnetic search coils. The vestibular stimulus consisted of low-amplitude, high-acceleration, passive, unpredictable, horizontal rotations of the head with respect to the trunk. While these so called head “impulses” had amplitudes of only 15–20 degrees with peak velocities up to 250 deg/s, they had peak accelerations up to 3000 deg/s/s. Fourteen humans were studied in this way before and after therapeutic unilateral vestibular neurectomy; 10 were studied 1 week or 1 year afterwards; 4 were studied 1 week and 1 year afterwards. The results from these 14 patients were compared with the results from 30 normal control subjects and with the results from one subject with absent vestibular function following bilateral vestibular neurectomy. Compensatory eye rotation in normal subjects closely mirrored head rotation. In contrast there was no compensatory eye rotation in the first 170 ms after the onset of head rotation in the subject without vestibular function. Before unilateral vestibular neurectomy all the patients' eye movement responses were within the normal control range. One week after unilateral vestibular neurectomy however there was a symmetrical bilateral HVOR deficit. The asymmetry was much more profound than has been shown in any previous studies. The HVOR generated in response to head impulses directed away from the intact side largely by ampullofugal disfacilitation from the single intact HSCC (ignoring for the moment the small contribution to the HVOR from stimulation of the vertical SCCs), was severely deficient with an average gain (eye velocity/head velocity) of 0.25 at 122.5 deg/sec head velocity (normal gain=0.94+/−0.08). In contrast the HVOR generated in response to head impulses directed toward the intact side, largely by ampullopetal excitation from the single intact HSCC, was only mildly (but nonetheless significantly) deficient, with an average gain of 0.80 at 122.5 deg/sec head velocity. At these accelerations there was no significant improvement in the average HVOR velocity gain in either direction over the following year. These results indicate that ampullopetal excitation from one HSCC can, even in the absence of ampullofugal disfacilitation from the opposite HSCC, generate a near normal HVOR in response to high-acceleration stimulation. Furthermore, since ampullofugal disfacilitation on its own, can only generate an inadequate HVOR in response to high-acceleration stimulation, it may under some normal circumstances make little contribution to the bilaterally generated HVOR.     

Off-center yaw rotation: effect of naso-occipital linear acceleration on the nystagmus response of normal human subjects and patients after unilateral vestibular loss

 Dual search coils were used to record horizontal, vertical and torsional eye movement components of one eye during nystagmus caused by off-center yaw rotation (yaw centrifugation). Both normal healthy human subjects (n=7) and patients with only one functioning labyrinth (n=12) were studied in order to clarify how the concomitant linear acceleration affected the nystagmus response. Each subject was seated with head erect on the arm of a fixed-chair human centrifuge, 1 m away from the center of the rotation, and positioned to be facing along a radius; either towards (facing-in) or away from (facing-out) the center of rotation. Both yaw right and yaw left angular accelerations of 10°s^–2 from 0 to 200°/s were studied. During rotation a centripetal linear acceleration (increasing from 0 to 1.24×g units) was directed along the subject’s naso-occipital axis resulting in a shift of the resultant angle of the gravitoinertial acceleration (GIA) of 51° in the subject’s pitch plane and an increase in the total GIA magnitude from 1.0 to 1.59×g. In normal subjects during the angular acceleration off-center there were, in addition to the horizontal eye velocity components, torsional and vertical eye velocities present. The magnitude of these additional components, although small, was larger than observed during similar experiments with on-center angular acceleration (Haslwanter et al. 1996), and the change in these components is attributed to the additional effect of the linear acceleration stimulation. In the pitch plane the average size of the shift of the axis of eye velocity (AEV) during the acceleration was about 8° for a 51° shift of the GIA (around 16% of the GIA shift) so that the AEV-GIA alignment was inadequate. There was a very marked difference in the size of the AEV shift depending on whether the person was facing-in [AEV shift forward (i.e. non-compensatory) of about 4°] or facing-out [AEV shift forward (i.e. compensatory) of around 12°]. The linear acceleration decreased the time constant of decay of the horizontal component of the post-rotatory nystagmus: from an average of 24.8°/s facing-in to an average of 11.3°/s facing-out. The linear acceleration dumps torsional eye velocity in an manner analogous to, but independent of, the dumping of horizontal eye velocity. Patients with UVD had dramatically reduced torsional eye velocities for both facing-in and facing-out headings, and there was little if any shift of the AEV in UVD patients. The relatively small effects of linear acceleration on human canal-induced nystagmus found here confirms other recent studies in humans (Fetter et al. 1996) in contrast to evidence from monkeys and emphasizes the large and important differences between humans and monkeys in otolith-canal interaction. Our results confirm the vestibular control of the axis of eye velocity of humans is essentially head-referenced whereas in monkeys that control is essentially space-referenced. Received: 22 September 1997 / Accepted: 30 June 1998     

Cellular and antibody response to respiratory syncytial (rs) virus in human colostrum,maternal blood,and cord blood

Samples of colostrum, maternal blood, and cord blood from a group of 21 women were examined for the presence of cellular reactivity to respiratory syncytial (RS) virus using a transformation assay and for the level of specific IgA, IgG, and IgM antibodies to RS virus by membrane immunofluo-rescence. Six of the 18 colostral cell cultures and six of the 16 maternal blood cultures gave a significant proliferative response to RS virus antigen, although a positive response in both local and systemic cell cultures was found in only one mother. In addition, one of 18 samples of cord blood gave a proliferative response to RS virus antigen. Detectable titres of IgA antibodies to RS virus were found in 15 of the 20 samples of colostral whey and in 13 of the 17 samples of maternal plasma examined. RS virus-specific IgG antibodies were detected in 10 of 20 colostral whey samples and in all samples of maternal cord plasma. In this study, it was not possible to demonstrate a relationship between a positive proliferative response of colostral cell cultures to RS virus and the level of specific IgA or IgG antibodies in colostral whey. Similarly, the proliferative response of maternal blood cultures was unrelated to the titre of specific IgA or lgG antibodies in maternal plasma. The relevance of the local cellular proliferative response to RS virus in colostral cell cultures to the protection afforded by breast-feeding is discussed.     

Collateralization of cerebellar efferent projections to the paraoculomotor region,superior colliculus,and medial pontine reticular formation in the rat: a fluorescent double-labeling study

Summary Collateralization of cerebellar efferent projections to the oculomotor region, superior colliculus (SC), and medial pontine reticular formation (mPRF) was studied in rats using fluorescent tracer substances. In one group, True Blue (TB) was injected into the oculomotor complex (OMC), including certain paraoculomotor nuclei and supraoculomotor ventral periaqueductal gray (PAG), and Diamidino Yellow (DY) was injected into the medial pontine reticular formation (mPRF) or pontine raphe. The largest number of single-TB-labeled (paraoculomotor-projecting) cells was observed in the medial cerebellar nucleus (MCN) and posterior interposed nucleus (PIN), whereas the largest number of single-DY-labeled (mPRF-projecting) cells was in the MCN. Double-TB/DY-labeled cells were present in the caudal two-thirds of the MCN, suggesting that some MCN neurons send divergent axon collaterals to the paraoculomotor region and mPRF. In another group, TB was injected into the SC and DY into the mPRF. The largest number of single-TB-labeled (SC-projecting) cells was in the PIN, although a considerable number of cells was observed in the caudal MCN, and ventral lateral cerebellar nucleus (LCN). Single-DY-labeled (mPRF-projecting) neurons were primarily located in the central and ventral MCN, but were also present in the lateral anterior interposed (AIN) and in the LCN. Double-TB/DY-labeled neurons were observed in the caudal two-thirds of the MCN and in the central portion of the LCN. The most significant new findings of the study concerned the MCN, which not only contained neurons that projected independently to the paraoculomotor region, SC, and mPRF, but also contained a considerable number of cells which collateralized to project to more than one of these nuclei. The possibility that the MCN projects to the supraoculomotor ventral PAG (containing an oculomotor interneuron system) and to the mPRF, which in the cat and monkey contain neural elements essential to the production of saccadic eye movements, is discussed. The anatomical findings suggest that the MCN in the rat plays an important role in eye movement.Abbreviations AI anterior interposed nucleus - AIN anterior interposed nucleus - BC brachium conjunctivum (sup. cerebellar peduncle) - dlh dorsolateral hump of the AI - dmc dorsomedial crest of the AI - IC inferior colliculus - ICP inferior cerebellar peduncle - Inf infracerebellar nucleus - L lateral cerebellar (dentate) nucleus - LCN lateral cerebellar (dentate) nucleus - M medial cerebellar (fastigial) nucleus - MCN medial cerebellar (fastigial) nucleus - MLF medial longitudinal fasciculus - mPRF medial pontine reticular formation (incl. nuc. reticularis pontis oralis and caudalis) - OMC oculomotor complex - OMN oculomotor nucleus - PI posterior interposed nucleus - PIN posterior interposed nucleus - RN red nucleus - SC superior colliculus - Vl lateral vestibular nucleus - Vs superior vestibular nucleus - Y cell group Y     

Sister chromatid exchange response of human diploid fibroblasts and chinese hamster ovary cells to dimethylnitrosamine and benzo(a)pyrene

In the search for relevant assays for mutagenicity testing, considerable attention has been given to the use of mammalian cells in vitro and the incorporation of metabolic activation in the protocol. Chinese hamster ovary (CHO) cells are commonly chosen as the target cells for cytogenetic tests because of their excellent growth characteristics and long lifespan in culture. However, there may be cellular factors affecting the uptake, metabolism, and repair of damage which are not the same in all cell lines. The response of CHO cells and three human diploid fibroblast strains (IMR-90, WI-38, S-3299) to benzo(a)pyrene (BP) and dimethylnitrosamine (DMN) were compared using sister chromatid exchange (SCE) analysis as a measure of genetic damage. For both BP and DMN the human cells and the CHO cells showed dose-response slopes that were significantly different from zero, except CHO cells treated with BP for 1 hr and S-3299 cells treated with DMN. Whereas human and CHO cells showed similar dose-responses to BP and the three human cell strains had similar dose-responses to BP and DMN, the dose-response of the human cells to DMN was statistically less significant than that of CHO cells. Reducing the duration of chemical treatment in CHO cells had no effect on the slope of the dose-response curves for BP or DMN. The observed differences between human and CHO cells may reflect differences in the fate of metabolic intermediates of DMN.     

Analysis of the human serological immune response to a variable region of the attachment (G) protein of respiratory syncytial virus during primary infection

The serum antibody responses of babies to the variable carboxy-terminal region of the attachment (G) protein of respiratory syncytial virus (RSV) have been analysed using paired acute and convalescent sera from infants experiencing their first RSV infection with viruses of known genotype. The variable 84–85 carboxy-terminal amino acids of the G protein of six recent isolates of group A RSV were expressed in Escherichia coli as fusion proteins with glutathione S-transferase. About half the infants developed antibodies which recognised these fusion proteins. The patterns of response obtained in enzyme linked immunosorbant assays and immunoblotting assays were closely related to the infecting genotype. © 1996 Wiley-Liss, Inc.     

Genetic and epitopic analysis of thyroid peroxidase (TPO) autoantibodies: markers of the human thyroid autoimmune response

TPO autoantibodies, the hallmark of human autoimmune thyroid disease, are of IgG class and are associated with thyroid destruction and hypothyroidism. Using the immunoglobulin gene combinatorial library approach, a panel of human monoclonal TPO autoantibodies (expressed as Fab) has been generated from thyroid tissue-infiltrating B cells. TPO-specific Fab closely resemble patients' serum autoantibodies in terms of L chain type, IgG subclass, affinities for TPO as well as epitopes recognized by > 80% of TPO autoantibodies in an individual's serum. TPO autoantibody V region genes are not unique; H chain V genes are usually mutated, while L chain V genes are sometimes in germ-line conformation. The autoantibodies recognize an immunodominant region involving conformational, overlapping epitopes in domains A and B. Finally, TPO autoantibody epitopic fingerprints are distinctive for individual sera, are not associated with hypothyroidism, but are conserved over time (indicating a lack of B cell epitope spreading). Evidence for conservation as well as inheritance of the fingerprints in some families, together with V_H gene polymorphisms, may provide insight into the genetic basis of human autoimmune thyroid disease. Furthermore, monoclonal human TPO autoantibodies will be invaluable for B cell presentation of TPO to determine the T cell epitopes involved in TPO autoantibody production.     

Isolation, tissue expression, and chromosomal assignment of a human LIM protein gene, showing homology to rat Enigma homologue (ENH)

Rat ENH (Enigma homolog) is a LIM domain protein that associates with protein kinase C in an isoform-specific manner. We have identified a human cDNA which shares a significant sequence homology with rat ENH. The isolated cDNA clone, designated human ENH (hENH), was 3287 bp in length and encoded a predicted protein of 596 amino acids which had 88% overall identity to rat ENH protein. Northern blot analysis revealed that 1.9 kb of the hENH messenger RNA was predominantly expressed in heart and skeletal muscle, while 5.6 kb of the hENH messenger RNA was ubiquitously expressed in various human tissues. The chromosomal location of the gene was determined on chromosome 4q22 region, between markers WI-2900 and WI-3273, by polymerase chain reaction (PCR)-based analyses using both a human/rodent monochromosomal hybrid cell panel and a radiation hybrid mapping panel. Received: February 25, 1999 / Accepted: April 3, 1999     

Analysis of the human antibody response to outer surface protein C (OspC) of Borrelia burgdorferi sensu stricto,B. garinii,and B. afzelii

The aim of this study was to determine by Western blotting (WB) the prevalence of anti-outer surface protein C (OspC) IgM and IgG antibodies in patients with Lyme borreliosis according to each of the three genospecies of Borrelia burgdorferi sensu lato. Strains of B. burgdorferi sensu stricto (MUL), B. garinii (DK 6), and B. afzelii (DK 26) served as antigen, all of which expressed abundant OspC. We examined sera from 117 patients with untreated early and late Lyme borreliosis, as well as from 100 blood donors and 29 patients with syphilis. WB results were compared with the B. burgdorferi flagellum enzyme-linked immunosorbent assay (ELISA) data. OspC from B. burgdorferi sensu stricto showed the lowest diagnostic sensitivity. OspC from B. garinii and B. afzelii performed almost identically in erythema migrans, with an IgM positive rate of 36% versus 34%, whereas OspC from B. garinii performed best in neuroborreliosis (60% versus 44%). The anti-OspC IgG response was less prominent than the IgM response and was infrequent in the late stages of the disease (0 – 20%). The benefit of combining the evaluation of anti-OspC responses with all three species was limited. The overall diagnostic sensitivity of WB anti-B. garinii OspC evaluation was, in the early stages of the disease, comparable to the results obtained using the flagellum ELISA. In erythema migrans and neuroborreliosis, the addition of anti-OspC IgM to the flagellum ELISA increased the sensitivity by 15% and 10%, respectively. It can, therefore, be concluded that OspC from B. garinii is a suitable OspC test antigen, and that supplementary use of OspC from other species adds little to the overall diagnostic sensitivity. An ELISA based on B. garinii OspC and native flagella seems currently the most promising concept for a future antibody test in early Lyme borreliosis. Received: 6 September 1996     

Reactions of the decentralized and denervated (pre- and postganglionic) human parotid gland to reflex stimulation,pilocarpine, proserine and atropine

Summary The characteristic signs of decentralization (cortico-hemispheric and nucleo-bulbar) and denervation (pre-and postganglionic) of the human parotid gland are presented. These signs may be used for differential diagnosis. The significance of proserine and atropine as indicators of pre-and postganglionic denervation (proserine-atropine dissociation, atropine paradox) was demonstrated. The author illustrates the dual character of chemoreceptive postsynaptic transmission, namely, the presence of cholinopositive (cholinomimetic) phylogenetically older, and cholinonegative (cholinolytic, inhibitory) phylogenetically younger structures. Various special points of application of proserin, atropine, pilocarpine (acetylcholine) are given (within the range of the pre-and postsynaptic transmission).(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 50, No. 11, pp. 51–56, November, 1960     

Synergistic,additive, and antagonistic mutagenic responses to binary mixtures of benzo(a)pyrene and benzo(e)pyrene as detected by strains TA98 and TA100 in the salmonella/microsome assay

Binary mixtures of benzo(a)pyrene (B(a)P) and benzo(e)pyrene (B(e)P) produce synergistic mutagenic (comutagenic) responses in Salmonella typhimurium strain TA98 (a frameshift detector). The optimum enhancement (25 ×) was found at B(a)P concentration of 0.3 μg/plate and B(e)P concentration of 1.5 μg/plate. The response of strain TA100 (mostly a base-substitution detector) is opposite that of TA98, showing antagonism and additivity in similar concentration ranges.     

当归内酯拮抗环孢菌素A、氢化可的松及抗肿瘤药物的免疫抑制作用

目的：观察当归内酯（ＡＳＤＬ）对免疫抑制剂及抗肿瘤引起的免疫抑制作用的影响。方法：应用免疫抑制剂及抗肿瘤药物建立免疫功能低下的模型,使用不同剂量的ＡＳＤＬ进行体内外拮抗实验。结果：ＡＳＤＬ在６２．５,１２５．０,２５０．０μｇ／ｍｌ时,可部分或完全拮抗环孢菌素Ａ,丝裂霉素,Ｃ,５－氟尿嘧啶和阿糖胞苷对小鼠混合淋巴细胞培养反应（ＭＬＲ）的轻度抑制作用,部分拮抗氢化可的松对ＭＬＲ的重度抑制（抑制５０％     

Development of a co-culture device for the study of human tenocytes in response to the combined stimulation of electric field and platelet rich plasma (PRP)

One of the objectives of rotator cuff repairs is to achieve biological healing and recovery in the tendon-bone zone. Some clinical evaluations reported the feasibility of tendon healing based on the stimulations of electric field and platelet-rich plasma (PRP). However, because of lack of appropriate tool for in vitro primary culture under complicated conditions, the efficacy and standard protocol of these healing approaches are still controversial among clinical experts. In this study, a novel co-culture device was developed for the study of tenocytes proliferation under single and combined stimulations of electric field and PRP. The device was a culture well divided into three sub-chambers separated by a barrier and embedded with a pair of parallel plate electrodes. Tenocytes and PRP gel could be respectively loaded into the sub-chambers and cultured with interlinked medium. Hence, tenocytes could concurrently receive a uniform electric field and platelet-derived growth factors by diffusion. Results revealed that the proliferation of tenocytes could be significantly enhanced by these stimulations. The device provides a precise and practical approach for the in vitro study of tendon healing, especially for PRP study. Moreover, optimization of the conditions of electric field and PRP could be determined by in vitro screening procedure before surgery to provide a personalized therapy.