WO1993002635A1

WO1993002635A1 - Foramenous implant

Info

Publication number: WO1993002635A1
Application number: PCT/US1992/005747
Authority: WO
Inventors: Ronald W. Dudek; Ronald S. Hill; James H. Brauker
Original assignee: Baxter International Inc.
Priority date: 1991-07-30
Filing date: 1992-07-09
Publication date: 1993-02-18
Also published as: NO931168L; CA2092825A1; EP0555428A1; JPH06502577A; NO931168D0

Abstract

A chamber made of a biocompatible material, adapted to be implanted in a host, adapted to substantially contain biological material immunologically compatible with the host, having a wall, having holes traversing the wall where the holes have an inner diameter at the narrowest point large enough to permit a functional host capillary to traverse the thickness of the wall, and where said holes are numerous enough to permit said host capillary to support the viability of the contained biological material.

Description

FORAMEN0US IMPLANT

FIELD OF INVENTION

This invention relates to an implant device and method for vascularlzatlon of implanted, immunologically compatible biological materi al .

Background of the Invention

Many diseases are due to a lack or destruction of a specific biological system. Examples include diabetes (lack of islet function), growth retardation (lack of growth hormone), other endocrine deficiencies (thyroid, parathyroid, reproductive, adrenal, pituitary), Parkinson's (lack of dopamine), hemophilia (lack of blood clotting factors), and inborn errors of metabolism (missing a specific enzyme or cofactor). in each instance the disease state results from a lack of a specific biologically produced factor.

Correction of these disease states requires the replacement of the specific biological function. For example, the diabetic must respond to minute to minute changes in blood glucose with an appropriate release of pancreatic hormones to maintain normal blood glucose concentrations. Diabetics treated with insulin do not maintain normal blood glucose levels. Implantation of functionalis lets of Langerhans cures the disease, insulin therapy merely treats the disease.

Several approaches to implanting living cells or tissue and devices have been attempted. Vacanti and Langer have developed a system described in "Chimeric Neomorphogenesis of Organs by Controlled Cellular Implantation Using Artificial Matrices", WO Patent Application No. 88/03785. This system is a tree-like matrix of biodegradable polymer on which cells are grown for subsequent implantation. The device is implanted into the patient, host vascularlzation of the cells occurs, the matrix is degraded and a psuedo-organ theoretically remains. The formation of the final functional organ requires a complex interaction between the device and host in an undefined and uncontrollable manner. This device, should it fail for any reason, would be difficult to remove due to the extensive connections to the host.

Another approach for the formation of organ-like structures in immunologically compatible patients is described by Thompson, Anderson, and Maciag in "Device for Directed Neovascularization and Method for Same," WO Patent Application No. 89/07944. The key features of this approach are a biocompatible matrix, similar in structure to that of Vacanti and Langer, a coating of anglogenic growth factors which are used to induce in vivo directed neovascularization and subsequent implantation in patients. The resulting structure, termed an organoid, may be useful as an implantation site for cells of therapeutic importance. Alternatively, it may be possible to attach cells prior to implantation.

Valentini et al., U.S. Patent No. 4,877,029 describes a semipermeable nerve guidance channel which is composed of a channel with a cell impermeable smooth inner membrane face and an outer surface with longitudinally directed trabeculae in the size range of 1 to 20 microns. This trabecular configuration does not include holes which traverse the thickness of the device and does not allow vascular growth into the inner compartment.

Rone! et al., U.S. Patent No. 4,298,002 describes a porous hydrophillc chamber for implanting cells. This device does not permit the invasion of vascular elements within the chamber.

Dental and bone implants with pores in the 5 to 50 microns size range allow fibrotic ingrowth to anchor the implant within tissue, but do not provide a chamber for implanting cells and do not result in vascularlzation of implanted cells or tissue. Additional examples of prior, art include U.S. Patent No.

4,553,272 "Regeneration of Living Tissues by Growth of isolated

Cells in Porous Implant and Product Thereof" and U.S. Patent No.

4,378,016 "Artificial Endocrine Gland Containing Hormone Producing Cells."

SUMMARY OF THE INVENTION

Applicants' invention is a chamber made of a biocompatible material adapted to be implanted in a host, and to substantially contain biological material immunologically compatible with the host, said chamber having a wall, said wall having holes traversing the wall where the holes have an inner diameter at the narrowest point large enough to permit a host capillary to traverse the thickness of the wall, and where said holes are numerous enough to permit said host capillary to support the viability of the biological material which may be contained therein.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1. Cross section drawing of a chamber used for vascularlzing tissue within the chamber. The chamber is made of an outer housing, a foramenous membrane, o-ring spacer and sealing ring.

Figure 2A. Body weight changes of rats implanted with large hole chambers (70 x 110 micron holes). Individual body weight changes of 3 rats implanted with large hole chambers (● ,■ ,♦ ) are compared to sham controls. (O , N=3, mean ± SEM) and diabetic controls (♢ , N=3, mean + SEM). One diabetic animal died at 3 weeks. Values after 3 weeks are the mean of the 2 remaining diabetic controls. Each rat was implanted on day 0 with 2 chambers each containing 2000 islets. Membranes were punctured with a 30 gauge needle (70 x 110 micron holes) to form the large holes. All chambers were implanted into epldidymal fat pads. Chambers were removed as indicated by (*). Figure 2B. Body weight changes of rats implanted with intact (3 micron pore) chambers. Individual body weight changes of 3 rats implanted with intact membranes compared to the sham ( O ,N=3) and diabetic controls (♢ ,N=3). Animals were implanted exactly as in Figure 2A except the chamber contained 3 micron pores.

Figure 3. Non-fasting blood glucose concentrations of rats implanted with large hole chambers (70 x 110 micron holes). Blood glucose concentrations of the 3 animals with large hole device implants are compared to sham ( O ,N=3) and diabetic control

(♢ ,N=3) animals.

Figure 4. Non-fasting blood glucose concentrations of rats implanted with intact (3 micron pore) chambers. Blood glucose concentrations of the 3 animals implanted with 3 micron pore membrane are compared to sham ( O ,N=3) and diabetic control

(♢ ,N=3) animals.

Figure 5. Intraperltoneal glucose tolerance test (IP GTT) of rats implanted with large hole chambers (70 x 110 micron holes).

Results are the mean +. SEM of the curves for the 3 animals implanted with large hole chambers before implant ( ● ), 1 week before explant (♢). and 1 week after explant (♦ ) .

Figure 6. Intraperltoneal glucose tolerance test (IP GTT) of rats implantad with intact (3 micron pore) membranes. The results are the mean of the IP GTT curves of the 3 animals before implant (● ), 1 week before explant (♢ ), and 1 week after explant (♦ ).

Figure 7. Hematoxylin/eosin stained sections of a large hole chamber (70 x 110 micron holes). This chamber was explanted after

4 weeks. Numerous, large islet masses were evident in this large hole chamber. Extensive vasculature had invaded the tissue with capillaries evident within islets themselves. Similar results were noted from devices explanted at 7 and 9 weeks. Figure 8. Hematoxylin/eosin stained section of an intact (3 micron pore) membrane chamber. This chamber was explanted after 4 weeks. Despite the extensive vascular response surrounding the membrane, only a few, small islet areas were present within the chamber demonstrating the inability of the intact (3 micron pore) chamber to support theislet.

Figure 9. Light micrographs of 14 day fetal syngeneic lung tissue after implantation for 21 days in a chamber with 5 micron pores. Note the well differentiated, highly vascularlzed tissue within the chamber. This pore size prevented the outgrowth of the tissue within the chamber.

Figure 10. Light micrographs of 14 day fetal syngeneic lung tissue after implantation for 21 days in a chamber with 10 to 15 micron pores. Note the well differentiated, highly vascularlzed tissue within the device. This chamber also prevented the outgrowth of the implanted tissue.

Figure 11. Light micrographs of recombinant tissue after implantation in epldidymal fat pads for 8 days in a chamber with large holes (90 x 170 micron holes). The recombinant shows positive immunocytochemical staining for insulin (A) and glucagon (B). In addition, there is prolific morphogenesis of tubules and a high degree of vascularlty.

Figure 12. Light micrographs of pancreatic rudiments after implantation in epldidymal fat pads for 8 days in a chamber with large holes (90 x 170 micron holes). Pancreatic rudiments show insulin (A) and glucagon (B) positive cells, tubular morphogenesis and a high degree of vascularlty.

Figure 13. Histological appearance of another large hole chamber (70 x 110 micron holes) after 3 days implantation. Chambers containing about 500 islets in Lewis rats produced a rapid vascular response as shown by the large vessel coursing through the center of the chamber after only 3 days in the animals. Figure 14. Histological appearance of 3 micron pore chamber after 3 days implantation. Devices containing about 500 islets in Lewis rats lacked an intimate vascularlzation response within the tissue chamber.

DETAILED DESCRIPTION OF INVENTION

This invention is a chamber for substantially containing cells, cellular organelles or tissue. The chamber is made of biocompatible material adapted for implantation in a host. The chamber is constructed with holes that traverse the entire thickness of the chamber wall. The holes need not be straight or uniform. They may form an Irrgeular pathway from the exterior to the interior of the chamber. The holes have an inner diameter large enough to allow the ingrowth and egress of host capillaries to and from cells or tissue in the chamber. This device is termed herein a foramenous chamber. This chamber allows the host vascular system to support both viability and therapeutic effectiveness of biological material placed in the chamber. The entire chamber need not have holes in It so long as a portion of the chamber has enough holes to support the viability of the contained material. The upper limit of the hole size will vary with the particular application. If the biological material is to be completely contained in the chamber then the upper limit of the hole size will be determined by the size of the cells or material contained in the chamber. If complete containment is not necessary, then the holes may be any size which will substantially contain the biological material. If the material also contains some holes smaller than that necessary to allow capillaries through, it will not interfere with the operation of the chamber. Such smaller holes need not be avoided. The contained biological material may be any cell, cell combination, organoid, organ or tissue to be implanted into a host. The biological material is preferably immunologically compatible with the host. The chamber may be any host biocompatible material that can be safely implanted into the host. See for example Table I, page xi, in Concise Guide to Biomedical Polymers by J. W. Boretos (1973), listing stable and semlstable materials appropriate for use in this invention.

In the past, other attempts to implant tissue within a device into a host while taking advantage of the host vasculature have shown poor cell viability because nutrients were not made available to the cells at a sufficient rate. See Scharp, D. W. et al., "Islet lmmuno-isolation:The Use of Hybrid Artiflcal Organs to Prevent Islet Tissue Rejection" in World Journal of Surgery, Volume 8, pp. 221 to 229 (1984). In accordance with the present invention the size and number of holes are sufficient to support early and sustained cell viability because enough capillaries form rapidly enough following implantation to allow the provision of nutrients at an appropriate rate.

The chamber may be used for tissue or cell replacement in the correction of disease states. Allograft implants of cellular organelles or free cells to correct a disease state are currently performed most commonly by infusion into the portal circulation to allow the cells to lodge in the liver. The instant invention allows use of an alternate implant site that can be easily accessed and the chamber with its contents may be removed if necessary. The chamber allows the host to provide adequate nutrltinal support for the implanted tissue to correct a disease state. Accordingly, the chamber may be used for allograft transplant of human tissue.

It may also be used to implant a patient's own cells which have been genetically altered so that they produce a therapeutic product. Once cells have been transformed to express a gene and secrete a therapeutic product, a removable container for those cells is desirable. This chamber may also be used to contruct a hybrid bioartlflcial organ. The chamber allows the host to supply the bioartlflcial organ with an intimate vasculature so that nutrients are delivered to the organ, metabolic wastes are removed, and the therapeutic product made by the organ is delivered to the host.

The chamber can be used to enclose an inner intact cellular protectant membrane. Vascular elements penetrate the chamber and provide sufficient nutrient and waste exchange for the enclosed cells to survive and function to correct a diabetic animal.

The chamber can also be used to contain mlcroencapsulated cells or organelles to be implanted. By implanting the encapsulated tissue within the chamber a rapid vascularization will be stimulated and the capsules will be contained within a defined space for easy removal should the need arise.

In one embodiment of the invention the following components were used: a foramenous membrane; a housing to hold the membrane; an o-ring to provide a tissue space; and biological tissue (Figure 1). The structural housing supports the membrane and provides integrity. In a prefered embodiment it is made of titanium. However, housings of Teflon, polystyrene and polypropylene have also been made and the housing can be made from alternative biocompatible materials. The o-ring of appropriate thickness, such as about 10 to 250 micron, provides a space for cells or tissue. Typically the o-ring is made of silicone although o-rings of other biocompatible materials may be used.

Membranes with a nominal pore size of about 3 micron failed to induce a rapid vascular response wi thi n the chamber (Figure 14). Vascular elements were detected in these 3 micron pore membrane devices after 3 to 9 weeks of implantation, but the vessels were occluded with inadequate blood flow to the implanted tissue. This was shown by islets implanted within a 3 micron pore membrane device falling to correct diabetic-animals (Figures 2b, 4, 6, and 8). Thus, the lower limit of nominal pore size to induce an adequate vascular response is greater than about 3 micron. Membranes with nominal pore size of 5 to 15 micron induced a rapid vascular response (Figures 9 and 10). Holes up to and including those of 90 x 170 micron induced the response (Figures 7, 11, 12, and 13).

Alternative forms of the chamber are also possible. These include, but are not limited to, including a scaffolding for cellular attachment within the chamber; providing an intact immunoprotective membrane enclosing cellular elements within the chamber; using microencapsulated tissue within the device; making the o-ring of a material which will seal the membranes together eliminating the need for the housing; stacked membrane packets to provide additional space for implanted tissue; making the device in the form of hollow fibers; or sealing the membrane with techniques such as sonic welding that does not require a housing.

EXAMPLE I

In order to monitor the ability of the chambers to correct diabetes, diabetic Lewis rats were implanted with large hole membrane or intact membrane devices containing isolated syngeneic islets. Implanted animals were compared to sham operated and diabetic control animals.

Membrane Preparation and Device Description Discs of the test membrane (a teflon membrane with polyester fiber backing, 3.0 micron effective nominal pore size, Gore® 3 micron teflon #L10956) were sequentially washed in Freon-TE35 for 30 to 60 minutes, several changes of ethanol and then soaked for 45 minutes in ethanol. The ethanol was removed with a sterile saline wash (0.95. NaCl). Membranes were transferred to culture medium (RPMI 1640 + 10% Fetal Bovine serum, FBS) and placed in a 37°C CO₂ incubator. Half of the membranes were left intact (3 micron pores) and half were perforated 24 times with a 30G sterile needle (large hole membranes, pore size 70 x 110 micron). Devices for holding the islets consisted of a titanium chamber with friction closure fitted with 2 test membrane discs separated by a 120 micron thick o-ring (Figure 1). Titanium chambers and silicon o-rlngs were sterilized by soaking in ethanol and rinsed in sterile saline before use. Inducing Diabetes

Diabetes was induced by 90% pancreatectomy (Px) followed by I.V. injection with streptozotodn (Stz) at 60 mg/kg body weight via the tall vein 3 to 10 days post-pancreatectomy. Adult Rat Islet Isolation

Islets from syngeneic Lewis rats were used for implantation. Following sacrifice, under aseptic conditions, the common bile duct was cannulated and the pancreas inflated with 10 ml of Hank's balanced salt solution (HBSS). The inflated pancreas was removed, cleaned and minced. Minced tissue was digested with collagenase (type V, Sigma) at 10 mg per pancreas in a 39°C water bath. Digestion was stopped with Ice-cold HBSS and the contents washed 3 times with HBSS. Islets were separated from adnar and most ductal tissue by centrifugation in a bovine serum albumin (BSA) step gradient of 29%, 26%, 23%, and 20%. Islets were washed with RPMI 1640 medium with 10% fetal bovine serum and cultured at 37°C in air/5% CO₂ for 3 to 7 days before implantation.

Device Implanation

Islets were hand picked from the culture plates for loading the devices. Ten ul of islet suspension (approximately 2000

Islets) were loaded into each test device. Each animal received 2 devices (4000 is lets total). Animals were anesthetized with xylazine (5 mg/kg) and ketamine (65 mg/kg) and their epldidymal fat pads isolated through a small lower abdominal incision. One device was placed on each fat pad and covered wi th the fat pad . Devi ces were hel d i n pl ace with Nexaband (CRX Medical, Inc.) tissue adhesive. The abdominal muscle was closed with suture (4-0 gut) and the skin with stainless steel wound clips.

Assessment of Diabetes Correction

The functional state of the animals was evaluated by monitoring the following parameters: change in body weight, non-fasting blood glucose, intraperltoneal glucose tolerance, and histology of the implants and pancreatic remnants at the time of sacrifice. Periodic non-fasting blood glucose levels were assessed with an ExacTech™ Blood Glucose Meter (Medlsense) in blood obtained from a tall vein stick. The upper limit of detection of the ExacTech™ Blood Glucose Meter is 450 mg/dl. Values reported as 450 mg/dl are a minimal estimate of the actual blood glucose concentration. Intraperltoneal glucose tolerance tests (IP GTT) consist of an overnight fast, I. P. injection of glucose (2 g/kg body weight from a 20% glucose solution) and measuring blood glucose at 0 (before injection), 10, 30, 50, and 90 minutes. Body weights were monitored throughout the study.

Device Removal

Devices were explanted after 4, 7, and 9 weeks of implantation. Explantatlon consisted of isolating the epldidymal fat pads, Ugating with silk suture and removing the devices. Devices were fixed for histology, one in glutaraldehyde the other in Bouin's fixative. Following explant, non-fasting blood glucose levels, fasting IP GTT's and body weights were monitored to assess reversion to the diabetic state in those animals that had shown correction. After reversion was established, the animals were sacrificed, the pancreatic remnant removed and fixed in Bouin's for hlstological examination. Four groups (N=3 per group) of animals were monitored: sham operated controls, diabetic controls, large hole membrane chamber implants (70 x 110 micron holes), and intact membrane chamber implants (3 micron pore).

Body Weight Changes

All 3 animals implanted with large hole membrane chambers gained weight at a rate comparable to or greater than sham controls (Figure 2A) during the period of implantation. In contrast, only one of the 3 animals implanted with intact membrane chambers gained weight comparable to control rats (Figure 2B). The diabetic control animals failed to gain weight.

Non-Fasting Blood Glucose

Large hole chamber implants reduced non-fasting blood glucose levels in all three animals to control levels (Figure 3). In all 3 animals, blood glucose levels rapidly rose to diabetic levels after device explantatlon. Animals implanted with intact membrane chambers had only slight, erratic reductions in non-fasting blood glucose after implantation (Figure 4). In no instance was glucose reduced to sham values. In fact, blood glucose remained at diabetic values.

Intraperltoneal Glucose Tolerance Tests (IP GTT) Islets in the large hole implants were functionally intact as shown by their acute response to a glucose challenge (Figure 5). With the large hole implants in the animals, their IP GTT curve was identical to the sham control curve. However, before implant and after explant their IP GTT curve was indistinguishable from the diabetic curve. In contrast, the intact membrane implants demonstrated only limited function (Figure 6). Histology

The large hole chambers contained large numbers of well vascularlzed islets (Figure 7). Capillaries were detected within the islets themselves. The intact membrane implant was also well vascularlzed on both the inside and outside of the chamber, but large blood islands formed within the device indicating a lack of freely flowing blood. In addition, only a small number ofislets were found within the chambers (Figure 8). Residual pancreas within the diabetic animals only contained sparse, badly damaged islet remnants.

The body weight changes, non-fasting blood glucose levels, IP GTT's, and histology demonstrate that the large hole implants corrected the diabetes of these 3 animals. The same parameters indicate that the intact membrane implants had only limited function and did not correct the diabetic state of the 3 animals with intact implants. The islets were maintained in a functional state in the large hole chambers because the chambers allow vascularlzation of the islets through the large holes in the chamber.

EXAMPLE 2

Implantation of fetal lung tissue in Gore^® 5 micron teflon (#X12039) membranes and Gore^® 10 to 15 micron teflon (#X12299) membranes with polyester backing.

Lung tissue from day 14 of gestation was isolated, minced into approximately 1 mm³ pieces, washed with DMEM, 20% FBS and placed in titanium chambers. The membranes used for this experiment were teflon with nominal pore size of either 5 or 10 to 15 micron. Devices were placed into epldidymal fat pads, left in the animals for 21 days and then explanted. Tissue was fixed in 2.5% glutaraldehyde and processed for hlstological examination.

Membranes with 5 micron nominal pore size allowed the fetal lung tissue to differentiate and mature and significant vascular response to the contained tissue was evident (Figure 9). Note that with the intact 5 micron pore membrane the tissue was contained within the device and did not grow out of the pores.

Membranes with 10 to 15 micron nominal pores also permitted the full differentiation and maturation of the implanted tissue (Figure 10). Again, tissue was contained within the interior of the chamber and was well vascularlzed.

EXAMPLE 3

Implantation of fetal pancreatic buds and tissue recombinants of fetal mesenchymal and adult ductal epithelium.

Gastric mesenchymal tissue and pancreatic rudiments were isolated from day 14 gestation Lewis rats and pancreatic ductal epithelium was isolated from adult Lewis rats. Recombinants were formed by carefully pipetting isolated ductal epithelium onto pieces of fetal mesenchyme within the tissue chamber device. Membranes used for these experiments were 0.45 micron pore teflon (MllUpore, CM) pierced with a 26 gauge needle 24 times to produce large holes (90 x 170 micron) in the upper membrane. The lower membrane was left intact.

The tissue chamber devices were implanted on the epldidymal fat pad of adult male Lewis rats. The epldidymal fat pad was pulled through a medial incision just anterior to the penis and laid on sterile gauze wetted with saline. The chamber was placed on the fat pad and the titanium ring was glued to the fat pad with tissue adhesive.

Recombinants (N=10) and pancreatic rudiments (N=6) were implanted for 8 days or 6 to 12 weeks. Chambers were explanted from the Lewis rats and fixed in Bouin's. After processing, sections were stained with hematoxylin and eosln and immunocytochemically stained for insulin and glucagon where appropriate. Recombinant tissues demonstrated significant tissue development as evidenced by the formation of tubules similar to those of intact pancreas. Cells immunoposltive for insulin and glucagon were detected after 8 days of implantation (Figure 11), demonstrating that differentiation had occurred. Similar morphogenesis was evident in the tissue explanted after 6 to 12 weeks. Endocrine tissue also differentiated in pancreatic rudiments as evidenced by immunostaining for insulin and glucagon after 8 days implantation (Figure 12). in all instances the implanted tissue was well vascularized. Thus, the large hol e membrane chambers were capable of supporting fetal tissue growth, morphogenesis and differentiation due to the substantial host vascularlzation. EXAMPLE 4

Rapid vascularlzation of isolated islets in large hole chambers (70 x 110 micron holes).

Membranes used for this experiment were 3 micron nominal pore teflon membranes (Gore® 3 micron Teflon #L10956) left intact (3 micron) or pierced with 70 x 1 10 micron holes. Approximately 500 pancreatic islets isolated from normal adult Lewis rats were placed within chambers in each configuration (N=2 per group). The chambers were implanted into the epldidymal fat pad of normal Lewis rats, explanted and examined histologlcally 3 days later.

At day 3 post-implantation with the large hole membrane chamber vessels were detected coursing through the interior of the chamber around the implanted islets (Figure 13). In contrast, islets implanted within the 3 micron pore chamber failed to be vascularlzed at 3 days post-implant (Figure 14).

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing i ts attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims

1. A chamber made of a biocompatible material,

(a) adapted to be implanted in a host,

(b) adapted to substantially contain biological material immunologically compatible with the host,

(c) having a wall,

(d) having holes traversing the wall where the holes have an inner diameter at the narrowest point large enough to permit a functional host capillary to traverse the thickness of the wall, and

(e) where said holes are numerous enough to permit said host capillary to support the viability of contained biological material.

2. The chamber of Claim 1 where the inner diameter at the narrowest point is greater than about three microns.

3. The chamber of Claim 1 where the inner diameter at the narrowest point is small enough so that the biological material is substantially contained in the chamber when implanted in the host.

4. The chamber of Claim 1 where the biocompatible material is teflon.

5. The chamber of Claim 1 in the configuration of a hollow fiber.

6. The chamber of Claim 1 containing living cells.

7. The chamber of Claim 6 where the living cells are capable of secreting a therapeutic product.

8. The chamber of Claim 6 where the living cells are pituitary cells, pancreatic islet cells, pancreatic beta cells, thyroid cells, parathyroid cells, or adrenal medullary cells.

9. The chamber of Claim 7 where the living cells are growth hormone secreting cells, Factor VIII secreting cells or Factor IX secreting cells.

10. The chamber of Claim 1 having input and output ports for access to the contents of the chamber.

11. The chamber of Claim 6 where the living cells are microencapsulated.

12. The chamber of Claim 1 containing a matrix on which cells may adhere and grow.

13. The chamber of Claim 1 where the biological material immunologically compatible with the host is allograft or xenograph tissue contained in an immunoisolating membrane.

14. A method comprising implanting the chamber of Claim 6 into a host.

15. A method comprising implanting the chamber of Claim 7 into a host.

16. A method comprising implanting the chamber of Claim 13 into a host.